News: Research Highlights

Wed January 1, 2014

Properties of the ground 3F2 state and the excited 3P0 state of atomic thorium in cold collisions with 3He

We measure inelastic collisional cross sections for collisions between thorium (Th) and helium. We determine for Th 3F2-He the ratio of the momentum-transfer to Zeeman relaxation cross sections for collisions to be g~500 at 800 mK. For Th 3P0-He collisions, we observe no measureable quenching of this metastable state, even after 106 collisions. This allowed...
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Wed January 1, 2014

Time-resolved magnetic sensing with electronic spins in diamond

One of the most promising applications of quantum information is in precision metrology. In the past year we focused on magnetic sensing with NV centers in diamond, in particular focusing on techniques to extend magnetic field sensing at the nano-scale to time-dependent reconstruction of magnetic fields and spectroscopy.
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Wed January 1, 2014

Quantum Interference Between Independent Reservoirs in Open Quantum Systems

When a quantum system interacts with multiple reservoirs, the environmental effects are usually treated in an additive manner. We showed that that assumption breaks down for non-Markovian environments that have finite memory times. Specifically, we demonstrated that quantum interferences between independent environments could qualitatively modify the dynamics of the physical system. We illustrated that effect...
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Wed January 1, 2014

Buffer-gas loaded magneto-optical traps for Yb, Tm, Er, and Ho

Novel physics in areas like quantum information, cold controlled chemistry and precision measurements is predicted to be accessible with molecules at temperatures in the mK regime. These approaches require molecular beam sources which are unavailable at present. In particular, providing cold, slow and bright beams of a general set of molecules, ideally independent of their...
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Tue January 1, 2013

Quantum Nonlinear Optics: Strongly Interacting Photons

Quantum-optics researchers have been trying to achieve strong inter­actions between individual photons for decades. These interactions constitute a fundamental tool toward the ultimate control of light fields “quantum by quantum.” They can be used to realize deterministic two-qubit optical gates for scalable quantum computing and to produce highly correlated states for high-precision measurements. Also, they...
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Tue January 1, 2013

Attractive Photons in a Quantum Nonlinear Medium

In this paper, we demonstrate for the first time a bound state of two photons. We illuminate a dense and cold atomic ensemble with weak laser light underconditions of electromagnetically induced transparency to an atomic Rydberg state. When we detune the control laser coupling the unstable intermediate state to the Rydberg level, the probe photons...
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Tue January 1, 2013

Keldysh Approach for Non-equilibrium Phase Transitions in Quantum Optics: Beyond the Dicke Model in Optical Cavities

We investigated nonequilibrium phase transitions for driven atomic ensembles interacting with a cavity mode and coupled to a Markovian dissipative bath. In the thermodynamic limit and at low frequencies, we showed that the distribution function of the photonic mode was thermal, with an effective temperature set by the atom-photon interaction strength. That behavior characterized the...
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