# F. J. Duarte

Francisco Javier "Frank" Duarte (born 1 September 1954) is a Chilean-American laser physicist and author who has contributed widely to dye lasers, tunable lasers, multiple-prism optics, and quantum interferometry.

## Quotes

* The two photons are entangled and according to local realism, their polarization planes should become independent... a typical EPR situation. Already in 1948, observations... agreed with quantum mechanics, not with local realism.
** R. H. Dalitz and F. J. Duarte, John Clive Ward, Physics Today 53, 99-100 (2000).
* Regardless of the prophetic value of Dirac’s description [on interference] his was probably the first discussion... including a coherent beam of light. In other words, Dirac wrote the first chapter in laser optics.
** in Introduction to Lasers, F. J. Duarte (2003). Tunable Laser Optics. Elsevier Academic. p. 3. ISBN 0-12-222696-8.
* Feynman uses Dirac's notation to describe the quantum mechanics of stimulated emission... he applies that physics to... dye molecules... In this regard, Feynman could have predicted the existence of the tunable laser.
** in Introduction to Lasers, F. J. Duarte (2003). Tunable Laser Optics. Elsevier Academic. p. 3. ISBN 0-12-222696-8. (while discussing The Feynman Lectures on Physics).
* The Dirac notation, though originally applied to the propagation of single particles, also applies to describing the propagation of ensembles of coherent, or indistinguishable, photons.
** in Dirac Optics, F. J. Duarte (2003). Tunable Laser Optics. Elsevier Academic. p. 25. ISBN 0-12-222696-8.
* All the indistinguishable photons illuminate the array of N slits, or grating, simultaneously. If only one photon propagates, at any given time, then that individual photon illuminates the whole array of N slits simultaneously.
** in Dirac Optics, F. J. Duarte (2003). Tunable Laser Optics. Elsevier Academic. p. 26. ISBN 0-12-222696-8.
* The intimate relation between interference and diffraction has its origin in the interference equation itself.
** in Dirac Optics, F. J. Duarte (2003). Tunable Laser Optics. Elsevier Academic. p. 37. ISBN 0-12-222696-8.
* Multiple-prism arrays were first introduced by Newton (1704) in his book Opticks. In that visionary volume Newton reported on arrays of nearly isosceles prisms in additive and compensating configurations to control the propagation path and the dispersion of light. Further, he also illustrated slight beam expansion in a single isosceles prism.
** in The Physics of Multiple-Prism Optics, F. J. Duarte (2003). Tunable Laser Optics. Elsevier Academic. p. 57. ISBN 0-12-222696-8.
* The longer the cavity and the narrower the beam waist, the better the beam quality of the laser emission, or $|\langle x|s\rangle |^{2}\ =\sum _{j=1}^{\mathbb {N} }\,\Psi (r_{j})^{2}\ +2\sum _{j=1}^{\mathbb {N} }\,\Psi (r_{j}){\bigg\sum _{m=j+1}^{\mathbb {N} }\,\Psi (r_{m})cos(\Omega _{m}-\Omega _{j}){\bigg )}$
** in Pulsed Narrow-Linewidth Tunable Laser Oscillators, F. J. Duarte (2003). Tunable Laser Optics. Elsevier Academic. p. 147. ISBN 0-12-222696-8.
* Personally, I find the concept of a "final theory," or a "theory of everything," rather limiting. The fun of discovery will most likely last as long as the human race continues.
** in F. J. Duarte (2012). Laser Physicist. Optics Journal. p. 154. ISBN 978-0-9760383-1-3.
* The EPR claim of an "all values" spread in the coordinate depends on an idealized absolute and exact measurement of $p$ with $\Delta p\ =0$. Since this is physically impossible, the claim of "no physical reality" can be negated.
** in F. J. Duarte (2013). Quantum Optics for Engineers. New York: CRC. ISBN 978-1439888537.
* The most efficient and practical interpretation of quantum mechanics is... no interpretation at all.
** in F. J. Duarte (2013). Quantum Optics for Engineers. New York: CRC. ISBN 978-1439888537.
* As noted previously Bell's theorem is completely disconnected from the physics leading to $|\psi \rangle _{+}$, $|\psi \rangle _{-}$, $|\psi \rangle ^{+}$, and $|\psi \rangle ^{-}$ .
** in F. J. Duarte (2022). "3". Fundamentals of Quantum Entanglement. Bristol: Institute of Physics (UK). ISBN 978-0-7503-5265-9.
* From an interferometric perspective, there are no mysteries... and no paradoxes... in the physics of quantum entanglement.
** in F. J. Duarte (2022). "30". Fundamentals of Quantum Entanglement. Bristol: Institute of Physics (UK). ISBN 978-0-7503-5265-9.

## Quotes about Duarte

* One of Ward's few close friends at Macquarie is... Frank Duarte... the two make an odd couple - the restrained rather distant Englishman and the intense, earnest South American.
** G. Sheridan, Australian physicist wins Guthrie Medal, The Bulletin 101 (5239), 49-50 (1980).
* Ward was vocal in his denunciation of the trivia that filled up Senate agendas… suitably then, it was a close student associate of Ward’s, physics Ph. D. student Frank Duarte, who began to mobilize student opinion in favor of a change.
** B. Mansfield and M. Hutchinson, Liberality of Opportunity: A History of Macquarie University 1964-1989 (Hale and Iremonger, Sydney, 1992) p. 269
* The sciences revolted under the guidance of several student activists, Frank Duarte in particular... we were fortunate that Duarte somehow established close links to the Federal Government, which was now the source of all funds.
** J. C. Ward, Memoirs of a Theoretical Physicist (Optics Journal, New York, 2004) p. 26.
* In 1994, Duarte first reported on solid-state dye laser oscillators.
** R. G. Driggers, Encyclopedia of Optical Engineering (CRC, New York, 2003) p. 2853.
* After some algebra, a successive formula can be derived from Duarte's original equation.
** K. Osvay et al., Measurements of non-compensated angular dispersion and the subsequent temporal lengthening of femtosecond pulses in a CPA laser, Optics Communications 248, 201-209 (2005).
* Another connection with Newton's pioneering work on spectra has been found by Duarte in modern quantum optics.
** P. Rowlands (2018). Newton and Modern Physics. World Scientific. p. 176. ISBN 978-1786343291.

## External links

* Tunable Laser Optics at Google
* Duarte's biography at the Optical Society
* Duarte's home page