US 11,651,949 B2

7

providing the compensation DC voltage 229 to the in-plane
compensation electrodes 210 to trap ions in the ion trapping
region 212.

In the process for trapping ions, the in-plane compensa-
tion electrodes can be disposed in the plane in which the first
RF electrode 204, the second RF electrode 205, the RF
ground electrodes, and the ion trapping region 212 are
disposed. The in-plane compensation electrodes can include
comprise a first in-plane compensation electrode 211 and a
second in-plane compensation electrode 211. The first in-
plane compensation electrode 210 and the second in-plane
compensation electrode 211 can protrude from the substrate
wall 214 into the ion aperture 213 toward the ion trapping
region 212, such that the first in-plane compensation elec-
trode 210 is spaced apart from and opposes the second
in-plane compensation electrode 211.

In an embodiment, a process for trapping ions with
spherical ion trap 200 includes, applying a radiofrequency

voltage to first RF electrode 204 and second RF electrode 2

205, while the other electrodes (206-211, 218, 219 if pres-
ent) are electrically grounded or held at DC voltages for
compensation of stray electric fields present in the environ-
ment. Here, the ratios of the secular motion frequencies
along the three principal axes are determined by the geom-
etry of the electrodes near the position of the ion and the DC
and RF voltages, and can be set within a wide range to
optimize performance for the specific application. The ion(s)
is trapped at the geometric center of the electrodes.

Spherical ion trap 200 is advantageous over conventional
three-dimensional spherical Paul traps since spherical ion
trap 200 can be microfabricated so that spherical ion trap
200 can be mass produced at low unit cost. The RF elec-
trodes 204 and 205 are technically superior to conventional
machined three-dimensional spherical Paul traps. since
machining imperfections can be much smaller with micro-
fabrication than with conventional machining, and machin-
ing imperfections can lead to deviations from the desired
principal axis directions and secular frequencies as well as
excess micromotion. The spherical ion trap 200 may be
technically superior to conventional planar spherical Paul
traps since spherical ion trap 200 has high trapping effi-
ciency so that lower voltages are used for operation, which
provides reductions in the size, weight, and power of
deployed systems using the spherical ion trap 200 as com-
pared with conventional ion traps.

While one or more embodiments have been shown and
described, modifications and substitutions may be made

thereto without departing from the spirit and scope of the 5

invention. Accordingly, it is to be understood that the present
invention has been described by way of illustrations and not
limitation. Embodiments herein can be used independently
or can be combined.

All ranges disclosed herein are inclusive of the endpoints, 5

and the endpoints are independently combinable with each
other. The ranges are continuous and thus contain every
value and subset thereof in the range. Unless otherwise
stated or contextually inapplicable, all percentages, when
expressing a quantity, are weight percentages. The suflix (s)
as used herein is intended to include both the singular and
the plural of the term that it modifies, thereby including at
least one of that term (e.g., the colorant(s) includes at least
one colorants). Option, optional, or optionally means that
the subsequently described event or circumstance can or
cannot occur, and that the description includes instances
where the event occurs and instances where it does not. As

0

65

8

used herein, combination is inclusive of blends, mixtures,

alloys, reaction products, collection of elements, and the

like.

As used herein, a combination thereof refers to a combi-
nation comprising at least one of the named constituents,
components, compounds, or elements, optionally together
with one or more of the same class of constituents, compo-
nents, compounds, or elements.

All references are incorporated herein by reference.

The use of the terms “a,” “an,” and “the” and similar
referents in the context of describing the invention (espe-
cially in the context of the following claims) are to be
construed to cover both the singular and the plural, unless
otherwise indicated herein or clearly contradicted by con-
text. It can further be noted that the terms first, second,
primary, secondary, and the like herein do not denote any
order, quantity, or importance, but rather are used to distin-
guish one element from another. It will also be understood
that, although the terms first, second, etc. are, in some
instances, used herein to describe various elements, these
elements should not be limited by these terms. For example,
a first current could be termed a second current, and,
similarly, a second current could be termed a first current,
without departing from the scope of the various described
embodiments. The first current and the second current are
both currents, but they are not the same condition unless
explicitly stated as such.

‘The modifier about used in connection with a quantity is
inclusive of the stated value and has the meaning dictated by
the context (e.g., it includes the degree of error associated
with measurement of the particular quantity). The conjunc-
tion or is used to link objects of a list or alternatives and is
not disjunctive; rather the elements can be used separately or
can be combined together under appropriate circumstances.

What is claimed is:

1. A spherical ion trap for trapping ions, the spherical ion
trap comprising:
substrate comprising an electrical insulator and an ion
aperture bounded by a substrate wall such that the ion
aperture receives ions:

a first RF electrode disposed on the substrate in electro-
static communication with an ion trapping region and
that protrudes from the substrate wall into the ion
aperture toward the ion trapping region and receives
DC and RF voltage;

a second RF electrode disposed on the substrate in elec-
trostatic communication with the ion trapping region
and that protrudes from the substrate wall into the ion
aperture toward the ion trapping region, such that the
second RF electrode is spaced apart from the first RF
electrode, opposes the first RF electrode, and receives
the DC and RF voltage;
plurality of RF ground electrodes disposed on the
substrate in electrostatic communication with the ion
trapping region and that protrudes from the substrate
wall into the ion aperture toward the ion trapping
region, such that the RF ground electrodes are spaced
apart from each other and from the first RF electrode
and the second RF electrode, and receive a DC voltage;
and

the ion trapping region bounded by opposing first RF
electrode and second RF electrode and the RF ground
electrodes, such that:
the ion trapping region is diposed within the ion

aperture and receives ions that are selectively
trapped in the ion trapping region in response to
receipt of the DC and RF voltage by the first RF

ey



U.S. Patent May 16, 2023 Sheet 12 of 14 US 11,651,949 B2

200
* 229.2 226 224.2
220
226 224.4
202-215 203
~_[-201
216 216
é 247
ae
' 213 wf 222
Bla] (SE za
2i1| 212 [210 217 yy
OSARIEING) Na co! 229.1 226
i)
247 H
216 — 216
x

202-245 ‘>A 203

FIG. 12


U.S. Patent May 16, 2023 Sheet 3 of 14 US 11,651,949 B2

200

In
irq
In
i=
No
i)

202 ~\ 215
2 203

201 | 217
217
204
2
205
217
201 |217
222 L_ 7223
203 203
oop 215
203 | 201 | 203

FIG. 3


US 11,651,949 B2

9

electrode and the second RF electrode, and receipt of
the DC voltages by RF ground electrodes, and

the first RF electrode, the second RF electrode, the RF
ground electrodes, and the ion trapping region are
disposed in the same plane within the ion aperture.

2. The spherical ion trap of claim 1, further comprising a
first ancillary compensation electrode in electrostatic com-
munication with the ion trapping region and that receives a
first compensation DC voltage.

3. The spherical ion trap of claim 2, further comprising a
second ancillary compensation electrode in electrostatic
communication with the ion trapping region and that
receives a second compensation DC voltage.

4. The spherical ion trap of claim 3, wherein the first
ancillary compensation electrode opposes the second ancil-
lary compensation electrode across the ion trapping region.

5. The spherical ion trap of claim 4, wherein the first
ancillary compensation electrode and the second ancillary
compensation electrode are disposed out of the plane in

which the first RF electrode, the second RF electrode, the RF 2

ground electrodes, and the ion trapping region are disposed.

6. The spherical ion trap of claim 1, further comprising a
plurality of in-plane compensation electrodes in electrostatic
communication with the ion trapping region and that receive
compensation DC voltages.

7. The spherical ion trap of claim 6, wherein the in-plane
compensation electrodes are disposed in the plane in which
the first RF electrode, the second RF electrode, the RF
ground electrodes, and the ion trapping region are disposed.

8. The spherical ion trap of claim 7, wherein the in-plane
compensation electrodes comprise a first in-plane compen-
sation electrode and a second in-plane compensation elec-
trode.

9. The spherical ion trap of claim 8, wherein the first
in-plane compensation electrode and the second in-plane
compensation electrode protrude from the substrate wall into
the ion aperture toward the ion trapping region, such that the
first in-plane compensation electrode is spaced apart from
and opposes the second in-plane compensation electrode.

10. The spherical ion trap of claim 1, wherein a thickness
of the first RF electrode, the second RF electrode, the RF
ground electrodes, and the ion trapping region is from 50 um
to 5mm.

11. A process for trapping ions with a spherical ion trap,
the process comprising:

receiving, by an ion trapping region of a spherical ion

trap, a plurality of ions, the spherical ion trap compris-
ing:
a substrate comprising an electrical insulator and an ion

aperture bounded by a substrate wall such that the s

ion aperture receives the ions:
a first RF electrode disposed on the substrate in elec-
trostatic communication with an ion trapping region
and that protrudes from the substrate wall into the

ion aperture toward the ion trapping region and

receives DC and RF voltage;
second RF electrode disposed on the substrate in
electrostatic communication with the ion trapping
region and that protrudes from the substrate wall into
the ion aperture toward the ion trapping region, such
that the second RF electrode is spaced apart from the
first RF electrode, opposes the first RF electrode, and
receives the DC and RF voltage;

plurality of RF ground electrodes disposed on the
substrate in electrostatic communication with the ion
trapping region and that protrudes from the substrate
wall into the ion aperture toward the ion trapping

s

s

0

5

&

4

10

region, such that the RF ground electrodes are
spaced apart from each other and from the first RF
electrode and the second RF electrode, and receive a
DC voltage; and
the ion trapping region bounded by opposing first RF
electrode and second RF electrode and the RF
ground electrodes, such that:
the ion trapping region is diposed within the ion
aperture and receives ions that are selectively
trapped in the ion trapping region in response to
receipt of the DC and RF voltage by the first RF
electrode and the second RF electrode, and receipt
of the DC voltage by RF ground electrodes, and
the first RF electrode, the second RF electrode, the
RF ground electrodes, and the ion trapping region
are disposed in the same plane within the ion
aperture;

providing the first RF electrode and the second RF

electrode with DC and RF voltage:

providing the RF ground electrodes with the DC voltage;

forming a trapping potential field in the ion trapping

region by the DC voltage RF power and the DC
voltage: and

trapping the ions in the ion trapping region in response to

forming the trapping potential field from the DC and
RF voltages.

12. The process of claim 11, further comprising tuning the
trapping potential field to trap ions having a selected mass-
to-charge ratio in the ion trapping region and destabilizing
trajectories of other ions that do not have the selected
mass-to-charge ratio, resulting in the other ions not being
trapped in the ion trapping region.

13. The process of claim 11, wherein the spherical ion trap
further comprises a first ancillary compensation electrode in
electrostatic communication with the ion trapping region,
such that the first ancillary compensation electrode receives
a first compensation DC voltage; and

the process further comprises providing the first compen-

sation DC voltage to the first ancillary compensation
electrode to trap ions in the ion trapping region.

14. The process of claim 13, wherein the spherical ion trap
further comprises a second ancillary compensation electrode
in electrostatic communication with the ion trapping region
and that receives a second compensation DC voltage:

the first ancillary compensation electrode opposes the

second ancillary compensation electrode across the ion
trapping region; and

the process further comprises providing the second com-

pensation DC voltage to the second ancillary compen-
sation electrode to trap ions in the ion trapping region.

15. The process of claim 14, wherein the first ancillary
compensation electrode and the second ancillary compen-
sation electrode are disposed out of the plane in which the
first RF electrode, the second RF electrode, the RF ground
electrodes, and the ion trapping region are disposed.

16. The process of claim 11, wherein the spherical ion trap
farther comprises a plurality of in-plane compensation elec
trodes in electrostatic communication with the ion trapping
region and that receives a compensation DC voltage; and

the process further comprises providing the compensation

DC voltage to the in-plane compensation electrodes to
trap ions in the ion trapping region.

17. The process of claim 16, wherein the in-plane com-
pensation electrodes are disposed in the plane in which the
first RF electrode, the second RF electrode, the RF ground
electrodes, and the ion trapping region are disposed.



US 11,651,949 B2

3

Conventional spherical RF Paul ion traps can include
three-dimensional electrode structures to generate the elec-
tric fields for trapping ions or can include planar electrode
structures that have low ion trapping efficiency. The original
Paul ion trap is described in W. Paul, Electromagnetic traps
for charged and neutral particles, Rev. Mod. Phys. 62, 531
(1990), the disclosure of which is incorporated by reference
in its entirety. Some conventional ion traps includes a ring
electrode situated between two end-cap electrodes or a
toroidal configuration. The spherical ion trap described
herein overcomes technical deviancies of the conventional
ion traps and provides a high ion trapping efliciency with a
planar electrode structure that can be formed by microfab-
rication.

It has been discovered that the spherical ion trap described
herein can be used for compact and field-deployable atomic
clocks, among other applications. The spherical ion trap can
include a single electrically insulating wafer that is micro-
machined with metal patterned over some portions of the
wafer to form the trap electrodes. Relative to conventional
spherical RF Paul ion traps, the spherical ion trap described
herein provides a beneficial combination of high trapping
efficiency and compatibility with microfabrication tech-
niques, wherein the spherical ion trap can be mass produced
at low unit cost and with very small geometrical imperfec-
tions.

Spherical ion trap 200 can selectively trap ions. In an
embodiment, with reference to FIG. 1, FIG. 2, FIG. 3, FIG.
4, FIG. 5, FIG, 6, FIG. 7, FIG. 8, FIG. 9, FIG. 10, FIG, 11,
FIG. 12, FIG. 13, and FIG. 14, spherical ion trap 200
includes: a substrate 201 including an electrical insulator
and an ion aperture 213 bounded by a substrate wall 214
such that the ion aperture 213 receives ions; a first RF
electrode 204 disposed on the substrate 201 in electrostatic
communication with an ion trapping region 212 and that
protrudes from the substrate wall 214 into the ion aperture
2113 toward the ion trapping region 212 and receives DC and
RF voltage 225; a second RF electrode 205 disposed on the
substrate 201 in electrostatic communication with the ion
trapping region 212 and that protrudes from the substrate
wall 214 into the ion aperture 213 toward the ion trapping
region 212, such that the second RF electrode 205 is spaced
apart from the first RF electrode 204, opposes the first RF
electrode 204, and receives the DC and RF voltage 225; a
plurality of RF ground electrodes (206, 207, 208, 209)
disposed on the substrate 201 in electrostatic communication
with the ion trapping region 212 and that protrudes from the
substrate wall 214 into the ion aperture 213 toward the ion
trapping region 212, such that the RF ground electrodes

(206, 207, 208, 209) are spaced apart from each other and s

from the first RF electrode 204 and the second RF electrode
205, and receive a DC voltage 224; and the ion trapping
region 212 bounded by opposing first RF electrode 204 and
second RF electrode 205 and the RF ground electrodes, such

that; the ion trapping region 212 is disposed within the ion ;

aperture 213 and receives ions that are selectively trapped in
the ion trapping region 212 in response to receipt of the DC
voltage RF power 225 by the first RF electrode 204 and the
second RF electrode 205, and receipt of the DC voltage 224
by RF ground electrodes, and the first RF electrode 204, the
second RF electrode 205, the RF ground electrodes, and the
ion trapping region 212 are disposed in the same plane
within the ion aperture 213.

‘A number, size, and shape of the RF ground electrodes
can be selected to provide for adequate compensation of
stray fields or to provide a tailored electrostatic potential of
the ion trapping region 212.

4

In an embodiment, with reference to FIG. 7, FIG. 9, FIG.
10, and FIG. 14, spherical ion trap 200 includes a first
ancillary compensation electrode 218 in electrostatic com-
munication with the ion trapping region 212 and that
receives a first compensation DC voltage 228. In an embodi-
ment, with reference to FIG. 8, FIG. 9, FIG. 11, and FIG. 14,
spherical ion trap 200 includes a second ancillary compen-
sation electrode 219 in electrostatic communication with the
ion trapping region 212 and that receives a second compen-
sation DC voltage 228. In an embodiment, the first ancillary
compensation electrode 218 opposes the second ancillary
compen: ss the ion trapping region
212, as shown in FIG. 9 and FIG. 14. In an embodiment, first
ancillary compensation electrode 218 and the second ancil-
lary compensation electrode 219 are disposed out of the
plane in which the first RF electrode 204, the second RF
electrode 205, the RF ground electrodes, and the ion trap-
ping region 212 are disposed. A size and shape of first
ancillary compensation electrode 218 and the second ancil-
lary compensation electrode 219 can be selected to provide
for adequate compensation of stray fields or to provide a
tailored electrostatic potential of the ion trapping region 212.

In an embodiment, with reference to FIG. 4, FIG. 5, FIG.
6, FIG. 10, FIG. 11, FIG. 12, FIG. 13, and FIG. 14, spherical

5 ion trap 200 includes a plurality of in-plane compensation

electrodes (e.g., 210, 211) in electrostatic communication
with the ion trapping region 212 and that receives a com-
pensation DC voltage 229. The in-plane compensation elec-
trodes (e.g., 210, 211) are disposed in the plane in which the
first RF electrode 204, the second RF electrode 205, the RF
ground electrodes, and the ion trapping region 212 are
disposed. A number of the in-plane compensation electrodes
can be selected to provide for adequate compensation of
stray electric fields or to provide a tailored electrostatic
potential of the ion trapping region 212. In an embodiment,
with reference to FIG. 4, the in-plane compensation elec-
trodes include a first in-plane compensation electrode 210
and a second in-plane compensation electrode 211. In an
embodiment, the first in-plane compensation electrode 210
and the second in-plane compensation electrode 211 pro-
trude from the substrate wall 214 into the ion aperture 213
toward the ion trapping region 212, such that the first
in-plane compensation electrode 210 is spaced apart from
and opposes the second in-plane compensation electrode
211.
A thickness of the first RF electrode 204, the second RF
electrode 205, the RF ground electrodes, and the ion trap-
ping region 212 can be suflicient to form the trapping
potential field in the ion trapping region 212. It is contem-
plated that the thickness of the individual electrodes inde-
pendently can be from 50 ym to 10 mm, eg., 300 ym. A
length of the electrodes (204-211) can be selected based on
asize of the ion trapping region 212 desired in consideration
of the size (e.g., radius) of the ion aperture 213. It should be
appreciated that ion aperture 213 provides for communica-
tion of ions that are transmitted through ion aperture 213.
Some of the figures show disposal of electrical wiring
trace 217 that connects electrical contact pad 216 to a certain
electrode (e.g., 204-211) via electrical wiring trace 217. The
electrical contact pad 216 can electrically interconnect an
electrode (e.g., one of 204-211) to an power source such as
DC voltage source 220 or DC and RF voltage source 221, as
shown in FIG, 12, FIG. 13, or FIG. 14. In this manner, DC
voltage source 220 can provide various independent DC
voltage 224 (e.g., 224.1, 224.2, 224.3, 224.4, 224.5) via
voltage transmission lines 226 to RF ground electrode 206,
RF ground electrode 207, RF ground electrode 208, RF



U.S. Patent May 16, 2023 Sheet 8 of 14 US 11,651,949 B2

203 215 202
[ 200
201 —| _
223 —|_y
216
217

203 215 202

FIG. 8


U.S. Patent May 16, 2023 Sheet 5 of 14 US 11,651,949 B2

203

215 202

\ [ 200

201 —| -

223 — |» 213 KS

IN
>
iO

|
[

214

nel 7 \ vt

203 215 202

FIG. 5


U.S. Patent May 16, 2023 Sheet 4 of 14 US 11,651,949 B2
202-215 >A 203
1
200 t
~_|-201
216 216
217 1 |
we | 222
216
Lo
217
216 216
x

202

215

FIG. 4

203


US 11,651,949 B2

5

ground electrode 209, in-plane compensation electrode 210,
in-plane compensation electrode 211, first ancillary com-
pensation electrode 218, or second ancillary compensation
electrode 219, wherein the voltage waveforms (of eg.,
224.1, 224.2, 224.3, 224.4, 224.5) can be selected in view of
the desired ion trapping conditions. Moreover, DC and RF
voltage source 221 can provide RF transmission line 227 via
RF transmission line 227 to first RF electrode 204 and
second RF electrode 205, wherein the waveforms of RF
transmission line 227 can be selected in view of the desired
ion trapping conditions, e, ss-to-charge, shape or size
of ion trapping region 212, and the like.

Elements of spherical ion trap 200 can be made of a
material that is physically or chemically resilient in an
environment in which spherical ion trap 200 is disposed.
Exemplary materials include a metal, ceramic, thermoplas-
tic, glass, semiconductor, and the like. Some of the elements
of spherical ion trap 200 can be made of the same or different
material and can be monolithic in a single physical body or
can be separate members that are physically joined.

Spherical ion trap 200 can be made in various ways. It
should be appreciated that spherical ion trap 200 includes a
number of electrical or mechanical components, wherein
such components can be interconnected and placed in com-
munication (e.g., optical communication, electrical commu-
nication, mechanical communication, fluid communication,
and the like) by physical, chemical, or mechanical intercon-
nects. The components can be disposed on mounts that can
be disposed on a bulkhead for alignment or physical com-
partmentalization. As a result, spherical ion trap 200 can be
disposed in a terrestrial environment or space environment.
Elements of spherical ion trap 200 can be formed from
silicon, aluminum nitride, diamond, and the like although
other suitable materials, such ceramic, glass, or metal can be
used. According to an embodiment, the elements of spheri-
cal ion trap 200 are formed using semiconductor microfab-
rication techniques although the elements of spherical ion
trap 200 can be formed using other methods, such as 3D
printing, injection molding, or machining a stock material
such as block of material that is subjected to removal of
material such as by cutting, laser ablation, and the like,
Accordingly, spherical ion trap 200 can be made by additive
or subtractive manufacturing. In an embodiment, elements
of spherical ion trap 200 are selectively etched to remove
various different materials using different etchants and pho-
tolithographic masks and procedures. The various layers
thus formed can be subjected to joining by bonding to form
spherical ion trap 200.

In an embodiment, spherical ion trap 200 is fabricated by

cutting the shape shown, e.g., in FIG. 4, out of a single s

electrically insulating wafer and patterning metal electrodes
‘onto the areas each electrode. Cutting can be performed
using laser machining, chemical etching, ion milling, or
other microfabrication techniques. Metal patterning can be

performed, e.g., by shadow masked sputtering or evapora- 5

tion.

Spherical ion trap 200 has numerous advantageous and
unexpected benefits and uses. In an embodiment, a process
for trapping ions includes: receiving, by an ion trapping
region 212 of a spherical ion trap 200, a plurality of ions, the
spherical ion trap 200 including: a substrate 201 including
an electrical insulator and an ion aperture 213 bounded by a
substrate wall 214 such that the ion aperture 213 receives the
ions; a first RF electrode 204 disposed on the substrate 201
in electrostatic communication with an ion trapping region
212 and that protrudes from the substrate wall 214 into the
ion aperture 213 toward the ion trapping region 212 and

&

&

6
receives DC and RF voltage 225; a second RF electrode 205
disposed on the substrate 201 in electrostatic communication,
with the ion trapping region 212 and that protrudes from the
substrate wall 214 into the ion aperture 213 toward the ion
trapping region 212, such that the second RF electrode 205
is spaced apart from the first RF electrode 204, opposes the
first RF electrode 204, and receives the DC and RF voltage
225; a plurality of RF ground electrodes disposed on the
substrate 201 in electrostatic communication with the ion
trapping region 212 and that protrudes from the substrate
wall 214 into the ion aperture 213 toward the ion trapping
region 212, such that the RF ground electrodes are spaced
apart from each other and from the first RF electrode 204
and the second RF electrode 205, and receive a DC voltage
224; and the ion trapping region 212 bounded by opposing
first RF electrode 204 and second RF electrode 205 and the
RF ground electrodes, such that: the ion trapping region 212
is disposed within the ion aperture 213 and receives ions that
are selectively trapped in the ion trapping region 212 in
response to receipt of the DC voltage RF power 225 by the
first RF electrode 204 and the second RF electrode 205, and
receipt of the DC voltage 224 by RF ground electrodes, and
the first RF electrode 204, the second RF electrode 205, the
RF ground electrodes, and the ion trapping region 212 are

5 disposed in the same plane within the ion aperture 213:

providing the first RF electrode 204 and the second RF
electrode 205 with DC and RF voltage 225; providing the
RF ground electrodes with the DC voltage 224; forming a
trapping potential field in the ion trapping region 212 by the
DC and RF voltage 225 and the DC voltage 224; and
trapping the ions in the ion trapping region 212 in response
to forming the trapping potential field from the DC and RF
voltage 225 and the DC voltage 224.

The process for trapping ions can include tuning the
trapping potential field to trap ions having a selected mass-
to-charge ratio in the ion trapping region 212 and destabi-
lizing trajectories of other ions that do not have the selected
mass-to-charge ratio, resulting in the other ions not being
trapped in the ion trapping region 212.

In the process for trapping ions, the spherical ion trap 200
can include a first ancillary compensation electrode 218 in
electrostatic communication with the ion trapping region
212, such that the first ancillary compensation electrode 218
receives a first compensation DC voltage 228; and the
process can include providing the first compensation DC
voltage 228 to the first ancillary compensation electrode 218
to trap ions in the ion trapping region 212.

In the process for trapping ions, the spherical ion trap 200
can include a second ancillary compensation electrode 219
in electrostatic communication with the ion trapping region
212 and that receives a second compensation DC voltage
228; the first ancillary compensation electrode 218 opposes
the second ancillary compensation electrode 219 across the
ion trapping region 212; and the process can include pro-
viding the second shielding DC voltage 228 to the second
ancillary compensation electrode 219 to trap ions in the ion
trapping region 212.

In the process for trapping ions, the first ancillary com-
pensation electrode 218 and the second ancillary compen-
sation electrode 219 can be disposed out of the plane in
which the first RF electrode 204, the second RF electrode
205, the RF ground electrodes, and the ion trapping region
212 are disposed. In the process for trapping ions, the
spherical ion trap 200 can include a plurality of in-plane
compensation electrodes 210 in electrostatic communication,
with the ion trapping region 212 and that receives a com-
pensation DC voltage 229; and the process can include



U.S. Patent May 16, 2023 Sheet 7 of 14 US 11,651,949 B2

202 215

\_/

IN
iO

|_-201

|_-222

‘>A 203

FIG. 7


a2) United States Patent

Leibrandt et al.

2

US01165194

US 11,651,949 B2
May 16, 2023

(10) Patent No.:
(45) Date of Patent:

G4)

ay

(72)

(73)

(c29)

(22)
(65)

(60)

G)

(52)

SPHERICAL ION TRAP AND TRAPPING
IONS

Applicant: Government of the United States of
America, as represented by the
Secretary of Commerce, Gaithersburg,
MD (US)

Inventors: David Ray Leibrandt, Superior, CO

(US); David Brian Hume, Boulder, CO

(US); Roger Charles Brown, Atlanta,

GA (US); Jeffrey Aaron Sherman,

Louisville, CO (US)

GOVERNMENT OF THE UNITED
STATES OF AMERICA, AS
REPRESENTED BY THE
SECRETARY OF COMMERCE,
Gaithersburg, MD (US)

Assignee:

Subject to any disclaimer, the term of this
patent is extended or adjusted under 35
U.S.C. 154(b) by 0 days.

Appl. No.: 17/590,690
Filed: Feb. 1, 2022

Prior Publication Data
US 2022/0246419 Al Aug. 4, 2022

Related U.S. Application Data

Provisional application No. 63/144,066, filed on Feb.
1, 2021.

n Search
. HOLT 49/424; HO1J 49/4265
250/281, 282, 283
See application file for complete search history.

(58) Field of Clas:
CPC se

(56) References Cited
U.S. PATENT DOCUMENTS
5,379,000 A 1/1995 Brewer et al.
2005/0258364 Al* 11/2005 Whitehouse .. HOLS 49/42
250/283
2013/0009050 A1* 1/2013. Park HOLS 49/063
250/281

(Continued)

OTHER PUBLICATIONS,

Brewer, R.G., et al., “Planar ion microtraps”, Phys. Review A, 1992,
p. R6781-R6784, vol. 46 No. 11

(Continued)

Primary Examiner — Nicole M Ippolito
(74) Attorney, Agent, or Firm — Office of Chief Counsel
for National Institute of Standards and Technology

(57) ABSTRACT

A spherical ion trap includes a substrate and an ion aperture;
two RF electrodes in electrostatic communication with an
ion trapping region; RF ground electrodes in electrostatic
communication with the ion trapping region; and the ion
trapping region bounded by opposing RF electrodes and the
RF ground electrodes, such that: the ion trapping region is
disposed within the ion aperture and receives ions that are
selectively trapped in the ion trapping region in response to
receipt of DC and RF voltages by the RF electrodes, and
receipt of the DC voltages by RF ground electrodes, and the
first RF electrode, the second RF electrode, the RF ground
electrodes, and the ion trapping region are disposed in the
same plane within the ion aperture.

20 Claims, 14 Drawing Sheets

| 201

222

Int. Cl.
HOLS 49/42 (2006.01)
US. Cl.
cpc HOLS 49/424 (2013.01); HOLT 49/4265
(2013.01)
= 215
200 \
=
x Y



U.S. Patent May 16, 2023 Sheet 10 of 14 US 11,651,949 B2

202-215 oA 203
200
|_-201
216
|_-222
216
x

202-215 ‘>A 203

FIG. 10


U.S. Patent May 16, 2023 Sheet 9 of 14 US 11,651,949 B2

200
203 | 201 | 203
me N 215
203 203
2a | |_ 223
201 | 217
217
204
212
218 “NX, 219
205
217
201 |217
222 7223
203 203
ooo 216
203 | 201 | 203
x

FIG. 9


U.S. Patent May 16, 2023 Sheet 6 of 14 US 11,651,949 B2

FIG.6


US 11,651,949 B2

11

18. The process of claim 17, wherein the in-plane com-
pensation electrodes comprise a first in-plane compensation
electrode and a second in-plane compensation electrode.

19. The process of claim 18, wherein the first in-plane
compensation electrode and the second in-plane compensa-
tion electrode protrude from the substrate wall into the ion
aperture toward the ion trapping region, such that the first
in-plane compensation electrode is spaced apart from and
‘opposes the second in-plane compensation electrode.

20. The process of claim 11, wherein a thickness of the
first RF electrode, the second RF electrode, the RF ground
electrodes, and the ion trapping region is from 50 jm to 5
mm.

0

12


U.S. Patent May 16, 2023 Sheet 2 of 14 US 11,651,949 B2

203

215 202

\ [ 200

201 ~|

217
223 ~ | _y 213 <3
2

Nn)
mm
=)

We -------}--

> [

eS
>
[ °

YS

IND
iS
IN

XN
PS
| -f22222 =o]

vel

203 215 202

FIG. 2


U.S. Patent May 16, 2023 Sheet 13 of 14 US 11,651,949 B2

200
” \
225 227
203 215
r
201 ~ | + 7
2iti
1
223 ~_| 213 ey B &
al 216
(1
225

X
BR
a pbc

nT ae

215 202

FIG. 13


US 11,651,949 B2

1
SPHERICAL ION TRAP AND TRAPPING
IONS

CROSS REFERENCE TO RELATED,
APPLICATIONS

This application claims the benefit of U.S. Provisional
Application Ser. No. 63/144,066 (filed Feb. 1, 2021),
h is herein incorporated by reference in its entirety.

STATEMENT REGARDING FEDERALLY,
SPONSORED RESEARCH,

This invention was made with United States Government
support from the National Institute of Standards and Tech-
nology (NIST), an agency of the United States Department
of Commerce. The Government has certain rights in this
invention.

BRIEF DESCRIPTION

Disclosed is a spherical ion trap for trapping ions, the
spherical ion trap comprising: a substrate comprising an
electrical insulator and an ion aperture bounded by a sub-
strate wall such that the ion aperture receives ions; a first RF
electrode disposed on the substrate in electrostatic commu-
nication with an ion trapping region and that protrudes from
the substrate wall into the ion aperture toward the ion
trapping region and receives DC and RF voltage; a second
RF electrode disposed on the substrate in electrostatic com-
munication with the ion trapping region and that protrudes
from the substrate wall into the ion aperture toward the ion
trapping region, such that the second RF electrode is spaced
apart from the first RF electrode, opposes the first RF
electrode, and receives the DC and RF voltage: a plurality of
RF ground electrodes disposed on the substrate in electro-
static communication with the ion trapping region and that
protrudes from the substrate wall into the ion aperture
toward the ion trapping region, such that the RF ground
electrodes are spaced apart from each other and from the first
RF electrode and the second RF electrode, and ive a DC
voltage; and the ion trapping region bounded by opposing
first RF electrode and second RF electrode and the RF
ground electrodes, such that: the ion trapping region is
disposed within the ion aperture and receives ions that are
selectively trapped in the ion trapping region in response to
receipt of the DC and RF voltage by the first RF electrode
and the second RF electrode, and receipt of the DC voltages
by the RF ground electrodes, and the first RF electrode, the

second RF electrode, the RF ground electrodes, and the ion 5

trapping region are disposed in the same plane within the ion
aperture.

Disclosed is a process for trapping ions with a spherical
ion trap, the process comprising: receiving, by an ion

trapping region of a spherical ion trap, a plurality of ions, the

spherical ion trap comprising: a substrate comprising an
electrical insulator and an ion aperture bounded by a sub-
strate wall such that the ion aperture receives the ions; a first
RF electrode disposed on the substrate in electrostatic com-
munication with an ion trapping region and that protrudes
from the substrate wall into the ion aperture toward the ion
trapping region and receives DC and RF voltage; a second
RF electrode disposed on the substrate in electrostatic com-
munication with the ion trapping region and that protrudes
from the substrate wall into the ion aperture toward the ion
trapping region, such that the second RF electrode is spaced
apart from the first RF electrode, opposes the first RF

20

2

electrode, and receives the DC voltage RF power; a plurality
of RF ground electrodes disposed on the substrate in elec-
trostatic communication with the ion trapping region and
that protrudes from the substrate wall into the ion aperture
toward the ion trapping region, such that the RF ground
electrodes are spaced apart from each other and from the first
RF electrode and the second RF electrode, and receive DC
voltages; and the ion trapping region bounded by opposing
first RF electrode and second RF electrode and the RF
ground electrodes, such that: the ion trapping region is
disposed within the ion aperture and receives ions that are
selectively trapped in the ion trapping region in response to
receipt of the DC and RF voltages by the first RF electrode
and the second RF electrode, and receipt of the DC voltages
by the RF ground electrodes, and the first RF electrode, the
second RF electrode, the RF ground electrodes, and the ion
trapping region are disposed in the same plane within the ion
aperture; providing the first RF electrode and the second RF
electrode with DC and RF voltage: providing the RF ground
electrodes with the DC voltage; forming a trapping potential
field in the ion trapping region by the DC and RF voltages;
and trapping the ions in the ion trapping region in response
to forming the trapping potential field from the DC and RF
voltages.

BRIEF DESCRIPTION OF THE DRAWINGS

The following description cannot be considered limiting
in any way. Various objectives, features, and advantages of
the disclosed subject matter can be more fully appreciated
with reference to the following detailed description of the
disclosed subject matter when considered in connection with
the following drawings, in which like reference numerals
identify like elements.

FIG. 1 shows a plan view of a first side of a spherical ion
trap, according to some embodiments.

FIG. 2 shows a plan view of a second side of the spherical
ion trap of FIG. 1, according to some embodiments.

FIG. 3 shows a cross-section of the spherical ion trap of
FIG. 1, according to some embodiments.

FIG. 4 shows a plan view of a first side of a spherical ion
trap, according to some embodiments.

FIG. 5 shows a plan view of a second side of the spherical
ion trap of FIG. 4, according to some embodimen

FIG. 6 shows a perspective view of the spherical ion trap
of FIG. 4, according to some embodiments.

FIG. 7 shows a plan view of a first side of a spherical ion
trap, according to some embodiments.

FIG. 8 shows a plan view of a second side of the spherical
ion trap of FIG. 7. ording to some embodiments.

FIG. 9 shows a cross-section of the spherical ion trap of
FIG. 7, according to some embodiments.

FIG. 10 shows a plan view of a first side of a spherical ion
trap, according to some embodiments.

FIG. 11 shows a plan view of a second side of the
spherical ion trap of FIG. 10, according to some embodi-
ments.

FIG. 12 shows a plan view of a first side of a spherical ion
trap, according to some embodiments.

FIG. 13 shows a plan view of a second side of the
spherical ion trap of FIG. 12, according to some embodi-
ments.

FIG. 14 shows a cross-section of the spherical ion trap of
FIG. 12, according to some embodiments.

DETAILED DESCRIPTION,

A detailed description of one or more embodiments is
presented herein by way of exemplification and not limita-
tion.


U.S. Patent May 16, 2023 Sheet 1 of 14 US 11,651,949 B2

202 215

\_/

IN
iO

NS 201

«| 222

Ly

202 © 215 ‘>A 203

FIG. 1


US 11,651,949 B2

Page 2
(56) References Cited
U.S. PATENT DOCUMENTS.
2016/0181077 A1* 6/2016 Ouyang ............. HOS 49/0013
250/282

201910027365 A1* 1/2019 Chou HOIL 21/32139

OTHER PUBLICATIONS,

Devoe, R.G., “Elliptical ion traps and trap arrays for quantum
computation”, Physical Review A, 1998, p. 910-914, vol. 58 No. 2
Pearson, C.E., “Theory and Application of Planar Ton Traps”,
Masters thesis, Massachusetts Institute of Technology, 2006, p.
1-106.

Nisbet-Jones, P.B.R., et al., “A single-ion trap with minimized
ion-environment interactions”, Applied Physics B, 2016, p. 1-8, vol.
122 No. 57.

Opticlock, “Prototype commercial trapped ion optical atomic clock”,
Accessed Jan. 21, 2022, doi: www.opticlock.de/en/info.

Chen, J-S., “Ticking near the Zero-Point Energy: towards 1x10-18
Accuracy in Al+ Optical Clocks”, Ph. D. thesis, University of
Colorado, 2017, Accessed Jan. 21, 2022, doi: https://www.nist gov!
system files/documents/2017/12/29/chen_thesis_main.pdf.

Paul, W,, “Electromagnetic traps for charged and neutral particles”,
Reviews of Modem Physics, 1990, p. 531-540, vol. 6 No. 3.

* cited by examiner


U.S. Patent

203

May 16, 2023

Sheet 11 of 14

215

US 11,651,949 B2

202

IN
ID
iO

201 —| -

223 | _»

203

FIG. 11

215

\

202

vet


U.S. Patent May 16, 2023 Sheet 14 of 14 US 11,651,949 B2

200
220
226-~| L~ 226
228.1 | L~ 228.2
203 | 201 | 203
202 _ 215
203 203
222—~ _/ 228
201 | 217
217

iS
i00
nN
nN
is
ei
E
a
ity

Ino
IS
ln

In
ie
NI

nN
iq

IN
ae
i~

\is
E
L

202

Ino
I>
luo
Imo
he
IND
jo

FIG. 14