News: Research Highlights

Wed January 1, 2014

Quantum Nanophotonic Phase Switch with a Single Atom

In analogy to transistors in classical electronic circuits, a quantum optical switch is an important element of quantum circuits and quantum networks. Operated at the fundamental limit where a single quantum of light or matter controls another field or material system, it may enable fascinating applications such as long-distance quantum communication, distributed quantum information processing and...
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Research Highlights
Wed January 1, 2014

Scattering Resonances and Bound States for Strongly Interacting Rydberg Polaritons

We provided a theoretical framework, which described slow-light polaritons interacting via atomic Rydberg states. We used a diagrammatic method to analytically derive the scattering properties of two polaritons. We identified new parameter regimes where polariton-polariton interactions were repulsive. Furthermore, in the regime of attractive interactions, we identified multiple two-polariton bound states, calculated their dispersion, and...
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Research Highlights
Tue January 1, 2013

Probing Real-space and Time Resolved Correlation Functions with Many-body Ramsey Interferometry

We proposed to use Ramsey interferometry and single-site addressability, available in synthetic matter such as cold atoms or trapped ions, to measure real-space and time-resolved spin correlation functions. Those correlation functions directly probed the excitations of the system, which made it possible to characterize the underlying many-body states. Moreover, they contained valuable information about phase...
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Research Highlights
Tue January 1, 2013

Non-Equilibrium Fractional Quantum Hall State of Light

We investigated the quantum dynamics of systems, which involved small numbers of strongly interacting photons. Specifically, we developed an efficient method to investigate such systems when they were externally driven with a coherent field. Furthermore, we showed how to quantify the many-body quantum state of light via correlation functions. Finally, we applied that method to...
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News type:
Research Highlights
Tue January 1, 2013

Enhanced Anti-ferromagnetic Exchange between Magnetic Impurities in a Superconducting Host

It is generally believed that superconductivity only weakly affects the indirect exchange between magnetic impurities. If the distance r between impurities is smaller than the superconducting coherence length (), this exchange is thought to be dominated by RKKY interactions, identical to those in a normal metallic host. This perception is based on a perturbative treatment...
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Research Highlights
Tue January 1, 2013

Beyond Universal Long-Range van der Waals Interactions with Ultracold 6Li2 Molecules

We have found that collisional loss of ultracold 6Li2 molecules can be determined by physics beyond universal long-range van der Waals interactions [1]. Starting with a degenerate Fermi gas of 6Li produced by sympathetic cooling with bosonic 23Na, we form Li2 molecules by a magnetic field sweep around a narrow Feshbach resonance. The resulting molecules...
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Research Highlights
Tue January 1, 2013

Unconventional Magnetism via Optical Pumping of Interacting Spin Systems

We considered strongly interacting systems of effective spins, subject to dissipative spin-flip processes associated with optical pumping. We predicted the existence of novel magnetic phases in the steady state of that system, which emerged due to the competition between coherent and dissipative processes. Specifically, for strongly anisotropic spin-spin interactions, we found ferromagnetic, antiferromagnetic, spin-densitywave, and...
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Research Highlights
Tue January 1, 2013

Spin-Orbit Suppression of Cold Inelastic Collisions of Aluminum and Helium

Cold collisions between atoms play a critical role in much of atomic physics, being responsible for few-body interactions, thermalization, trap loss and decoherence.  The development of a detailed understanding of collisions is therefore crucial to the continued expansion of the field into new atomic systems, an expansion that has already led to the discovery of...
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Research Highlights
Tue January 1, 2013

Realizing Fractional Chern Insulators in Dipolar Spin Systems

Strongly correlated quantum systems can exhibit exotic behavior controlled by topology. We predicted that the v = 1/2 fractional Chern insulator arose naturally in a two-dimensional array of driven, dipolar interacting spins. As a specific implementation, we analyzed how to prepare and detect synthetic gauge potentials for the rotational excitations of ultracold polar molecules trapped...
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Research Highlights
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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News type:
Research Highlights