News: Research Highlights

Wed January 1, 2014

Interferometric Probes of Many-body Localization

We proposed a method for detecting many-body localization (MBL) in disordered spin systems. The method involved pulsed, coherent spin manipulations that probed the dephasing of a given spin due to its entanglement with a set of distant spins. It allowed one to distinguish the MBL phase from a non-interacting localized phase and a delocalized phase....
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Wed January 1, 2014

Many-body Dynamics of Dipolar Molecules in an Optical Lattice

Understanding the many-body dynamics of isolated quantum systems is one of the central challenges in modern physics. To this end, the direct experimental realization of strongly correlated quantum systems allows one to gain insights into the emergence of complex phenomena. Such insights enable the development of theoretical tools that broaden our understanding. In our study,...
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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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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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Tue January 1, 2013

Single-photon Nonlinearities in Two-mode Optomechanics

We presented a detailed theoretical analysis of a weakly driven, multimode optomechanical system, in which two optical modes were strongly and near-resonantly coupled to a single mechanical mode via a three-wave mixing interaction. We calculated one- and two-time intensity correlations of the two optical fields and compared them to analogous correlations in atom-cavity systems. Nonclassical...
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Tue January 1, 2013

Phonon-induced Spin-Spin Interactions in Diamond Nanostructures: Application to Spin Squeezing

We proposed and analyzed a novel mechanism for long-range spin-spin interactions in diamond nanostructures. The interactions between electronic spins, associated with nitrogen-vacancy centers in diamond, were mediated by their coupling via strain to the vibrational mode of a diamond mechanical nanoresonator. That coupling resulted in phonon-mediated effective spin-spin interactions that could be used to generate...
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Tue January 1, 2013

Robustness of Quantum Memories Based on Majorana Zero Modes

We analyzed the rate at which quantum information encoded in zero-energy Majorana modes was lost in the presence of perturbations. We showed that information could survive for times that scale exponentially with the size of the chain both in the presence of quenching and time-dependent quadratic dephasing perturbations, even when the latter had spectral components...
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Tue January 1, 2013

Stretchable Photonic Crystal Cavity with Wide Frequency Tunability

We reported a new approach for the realization of a flexible photonic crystal (PC) cavity that enabled wide-range tuning of its resonance frequency. Our PC cavity consisted of a regular array of silicon nanowires embedded in a polydimethylsiloxane (PDMS) matrix and exhibited a cavity resonance in the telecommunication band that could be reversibly tuned over...
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Tue January 1, 2013

Coherence and Raman Sideband Cooling of a Single Atom in an Optical Tweezer

We investigated quantum control of a single atom in a tightly focused optical tweezer trap. We showed that inevitable spatially varying polarization gave rise to significant internal-state decoherence but that the effect could be mitigated by an appropriately chosen magnetic bias field. That enabled Raman sideband cooling of a single atom close to its three-dimensional...
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Tue January 1, 2013

Topologically Protected Quantum State Transfer in a Chiral Spin Liquid

Topology plays a central role in ensuring the robustness of a wide variety of physical phenomena. Notable examples range from the current-carrying edge states associated with the quantum Hall and the quantum spin Hall effects to topologically protected quantum memory and quantum logic operations. We proposed and analysed a topologically protected channel for the transfer...
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