# Daniel J. Gauthier

Research Professor of Physics

Prof. Gauthier is interested in a broad range of topics in the fields of nonlinear and quantum optics, and nonlinear dynamical systems.

In the area of optical physics, his group is studying the fundamental characteristics of highly nonlinear light-matter interactions at both the classical and quantum levels and is using this understanding to develop practical devices.

At the quantum level, his group has three major efforts in the area of quantum communication and networking. In one project, they are investigating hybrid quantum memories where one type of memory is connected to another through the optical field (so-called flying qubits). In particular, they are exploring nonlinear optical methods for frequency converting and impedance matching photons emitted from one type of quantum memory (e.g., trapped ions) to another (e.g., quantum dots).

In another project, they are exploring methods for efficiently transmitting a large number of bits of information per photon. They are encoding information on the various photon degrees of freedom, such as the transverse modes, one photon at a time, and using efficient mode sorters to direct the photons to single-photon detectors. The experiments make use of multi-mode spontaneous down conversion in a nonlinear crystal to produce quantum correlated or entangled photon pairs.

Another recent interest is the development of the world's most sensitive all-optical switch. Currently, they have observed switching with an energy density as low as a few hundred yoctoJoules per atomic cross-section, indicating that the switch should be able to operate at the single-photon level. The experiments use a quasi-one-dimensional ultra-cold gas of rubidium atoms as the nonlinear material. They take advantage of a one-dimensional optical lattice to greatly increase the nonlinear light-matter interaction strength.

In the area of nonlinear dynamics, his group is interested in the control and synchronization of chaotic devices, especially optical and radio-frequency electronic systems. They are developing new methods for private communication of information using chaotic carriers, using chaotic elements for distance sensing (e.g., low-probability-of-detection radar), using networks of chaotic elements for remote sensing, and using chaotic elements for generating truly random numbers at high data rates. Recently, the have observed 'Boolean chaos,' where complex behavior is observed in a small network of commercially-available free-running logic gates.

## Appointments and Affiliations

- Research Professor of Physics
- Professor in the Department of Electrical and Computer Engineering
- Bass Fellow

## Contact Information

**Office Location:**Physics Bldg, 120 Science Dr., Durham, NC 27708**Office Phone:**(919) 660-2511**Websites:**

## Education

- Ph.D. University of Rochester, 1989
- M.S. University of Rochester, 1983
- B.S. University of Rochester, 1982

## Research Interests

Prof. Gauthier is interested in a broad range of topics in the fields of nonlinear and quantum optics, and nonlinear dynamical systems.

In the area of optical physics, his group is studying the fundamental characteristics of highly nonlinear light-matter interactions at both the classical and quantum levels and is using this understanding to develop practical devices.

At the quantum level, his group has three major efforts in the area of quantum communication and networking. In one project, they are investigating hybrid quantum memories where one type of memory is connected to another through the optical field (so-called flying qubits). In particular, they are exploring nonlinear optical methods for frequency converting and impedance matching photons emitted from one type of quantum memory (e.g., trapped ions) to another (e.g., quantum dots).

In another project, they are exploring methods for efficiently transmitting a large number of bits of information per photon. They are encoding information on the various photon degrees of freedom, such as the transverse modes, one photon at a time, and using efficient mode sorters to direct the photons to single-photon detectors. The experiments make use of multi-mode spontaneous down conversion in a nonlinear crystal to produce quantum correlated or entangled photon pairs.

Another recent interest is the development of the world's most sensitive all-optical switch. Currently, they have observed switching with an energy density as low as a few hundred yoctoJoules per atomic cross-section, indicating that the switch should be able to operate at the single-photon level. The experiments use a quasi-one-dimensional ultra-cold gas of rubidium atoms as the nonlinear material. They take advantage of a one-dimensional optical lattice to greatly increase the nonlinear light-matter interaction strength.

In the area of nonlinear dynamics, his group is interested in the control and synchronization of chaotic devices, especially optical and radio-frequency electronic systems.

They are developing new methods for private communication of information using chaotic carriers, using chaotic elements for distance sensing (e.g., low-probability-of-detection radar), using networks of chaotic elements for remote sensing, and using chaotic elements for generating truly random numbers at high data rates. Recently, the have observed 'Boolean chaos,' where complex behavior is observed in a small network of commercially-available free-running logic gates.

## Awards, Honors, and Distinctions

- Robert C. Richardson Professor of Physics. Duke University. 2011
- Outstanding Referee of the Physical Review and Physical Review Letters. American Physical Society. 2009
- Fellows. Optical Society of America. 2006
- Fellow. American Physical Society. 2002

## Courses Taught

- PHYSICS 791: SPECIAL READINGS

## In the News

- High-Speed Quantum Encryption May Help Secure The Future Internet (Nov 27, 2017)
- Cathy Li: A Better Approach to Machine Learning (Jul 9, 2014)
- Slaying dragon-kings could prevent financial crashes (Nov 21, 2013 | New Scientist )
- Using chaos theory to predict and prevent catastrophic 'dragon king’ events (Oct 30, 2013 | Wired )
- Market Bubbles May Be Predictable, Controllable (Oct 17, 2013)
- Pratt Engineers Awarded Four Department of Defense Grants (Jun 18, 2013)

## Representative Publications

- Cahall, C; Nicolich, KL; Islam, NT; Lafyatis, GP; Miller, AJ; Gauthier, DJ; Kim, J,
*Multi-photon detection using a conventional superconducting nanowire single-photon detector*, Optica, vol 4 no. 12 (2017), pp. 1534-1535 [10.1364/OPTICA.4.001534] [abs]. - Islam, NT; Lim, CCW; Cahall, C; Kim, J; Gauthier, DJ,
*Provably secure and high-rate quantum key distribution with time-bin qudits.*, Science Advances, vol 3 no. 11 (2017) [10.1126/sciadv.1701491] [abs]. - Stipčević, M; Christensen, BG; Kwiat, PG; Gauthier, DJ,
*Advanced active quenching circuit for ultra-fast quantum cryptography*, Optics express, vol 25 no. 18 (2017), pp. 21861-21861 [10.1364/OE.25.021861] [abs]. - Shea, ME; Gauthier, DJ,
*Comment on “Nondestructive light-shift measurements of single atoms in optical dipole traps”*, Physical Review A, vol 96 no. 2 (2017) [10.1103/PhysRevA.96.027401] [abs]. - Islam, NT; Cahall, C; Aragoneses, A; Lezama, A; Kim, J; Gauthier, DJ,
*Robust and Stable Delay Interferometers with Application to -Dimensional Time-Frequency Quantum Key Distribution*, Physical review applied, vol 7 no. 4 (2017) [10.1103/PhysRevApplied.7.044010] [abs].