News: Research Highlights

Tue January 1, 2013

Coupling of NV Centers to Photonic Crystal Nanobeams in Diamond

The realization of efficient optical interfaces for solid-state atom-like systems is an important problem in quantum science with potential applications in quantum communications and quantum information processing. We described and demonstrated a technique for coupling single nitrogen vacancy (NV) centers to suspended diamond photonic crystal cavities with quality factors up to 6000. Specifically, we presented...
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Tue January 1, 2013

Nanometer-scale Thermometry in a Living Cell

Sensitive probing of temperature variations on nanometre scales is an outstanding challenge in many areas of modern science and technology. In particular, a thermometer capable of subdegree temperature resolution over a large range of temperatures as well as integration within a living system could provide a powerful new tool in many areas of biological, physical...
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Tue January 1, 2013

Collectively Enhanced Interactions in Solid-state Spin Qubits

We proposed and analyzed a technique to collectively enhance interactions between solid-state quantum registers composed from random networks of spin qubits. In such systems, disordered dipolar interactions generically result in localization. In our study, we demonstrated the emergence of a single collective delocalized eigenmode as one turned on a transverse field. The interaction strength between...
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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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Tue January 1, 2013

All-optical Sensing of a Single-molecule Electron Spin

We demonstrated an all-optical method for magnetic sensing of individual molecules in ambient conditions at room temperature. Our approach was based on shallow nitrogen-vacancy (NV) centers near the surface of a diamond crystal, which we used to detect single paramagnetic molecules covalently attached to the diamond surface. The manipulation and readout of the NV centers...
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Tue January 1, 2013

Dissipative Preparation of Spin Squeezed Atomic Ensembles in a Steady State

We presented and analyzed an approach for the generation of atomic spin-squeezed states. Our method involved the collective coupling of an atomic ensemble to a decaying mode of an open optical cavity. We demonstrated the existence of a collective atomic dark state, decoupled from the radiation field. Through the explicit construction of that state we...
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Tue January 1, 2013

Experimentally efficient methods for estimating the performance of quantum measurements

In this work we proposed metrics to characterize the performance of quantum measurements and provided experimentally accessible and efficient protocols to estimate these metrics. This work thus fills a gap in the characterization of quantum operations, which has until now focused on just the system evolution (via techniques such as quantum process tomography) providing a...
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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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