Patent Number: 
Section: claims

1. A three-dimensional grating magneto optical trap (3D GMOT) comprising:a single input light beam having its direction along a first axis, an area along a second and third axis that are both normal to the first axis, and a substantially flat input light beam intensity profile extending across its area;a circular, diffraction-grating surface positioned normal to the first axis and extending along the second and third axis; the circular, diffraction-grating surface having closely adjacent grooves arranged concentrically around a gap formed in the center of the circular, diffraction-grating surface;the circular, diffraction-grating surface configured to:diffract first-order light beams that intersect within an intersection region that lies directly above the gap, andsuppresses reflections and diffractions of all other orders; anda quadrupole magnetic field with its magnitude being zero within the intersection region;wherein the 3D GMOT is configured to trap a cold-atom cloud within the intersection region. 2. The 3D GMOT of claim 1, wherein each of the diffracted first-order light beam's intensity is between 15 and 35% of the input light beam's intensity. 3. A method for trapping a cold-atom cloud, the method comprising providing a three-dimensional grating magneto optical trap (3D GMOT), comprising:providing a first, single input light beam having its direction along a first axis, an area along a second and third axis that are both normal to the first axis, and a substantially flat input light beam intensity profile extending across its area;providing a circular, diffraction-grating surface positioned normal to the first axis and extending along the second and third axis; the circular, diffraction-grating surface having closely adjacent grooves arranged concentrically around a gap formed in the center of the circular, diffraction-grating surface;the circular, diffraction-grating surface configured to:diffract first-order light beams that intersect within an intersection region that lies directly above the gap, andsuppresses reflections and diffractions of all other orders; andproviding a quadrupole magnetic field with its magnitude being zero within the intersection region;wherein the 3D GMOT is configured to trap the cold-atom cloud within the intersection region. 4. The method of claim 3, wherein each of the diffracted first-order light beam's intensity is between 15 and 35% of the input light beam's intensity.