53 research outputs found
Role reversal in a Bose-condensed optomechanical system
We analyze the optomechanics-like properties of a Bose-Einstein condensate
(BEC) trapped inside an optical resonator and driven by both a classical and a
quantized light field. We find that this system exhibits a nature of role
reversal between the matter-wave field and the quantized light field. As a
result, the matter wave field now plays the role of the quantized light field,
and the quantized light field behaves like a movable mirror, in contrast to the
familiar situation in BEC-based cavity optomechanics [Brennecke et al., Science
322, 235 (2008); Murch et al., Nat. Phys. 4, 561 (2008)]. We demonstrate that
this system can lead to the creation of a variety of nonclassical matter-wave
fields, in particular cat states, and discuss several possible protocols to
measure their Wigner function
One qubit and one photon -- the simplest polaritonic heat engine
Hybrid quantum systems can often be described in terms of polaritons. These
are quasiparticles formed of superpositions of their constituents, with
relative weights depending on some control parameter in their interaction. In
many cases, these constituents are coupled to reservoirs at different
temperatures. This suggests a general approach to the realization of
polaritonic heat engines where a thermodynamic cycle is realized by tuning this
control parameter. Here we discuss what is arguably the simplest such engine, a
single qubit coupled to a single photon. We show that this system can extract
work from feeble thermal microwave fields. We also propose a quantum
measurement scheme of the work and evaluate its back-action on the operation of
the engine.Comment: 8 pages, 4 figures, new contents adde
Light scattering detection of quantum phases of ultracold atoms in optical lattices
Ultracold atoms loaded on optical lattices can provide unprecedented
experimental systems for the quantum simulations and manipulations of many
quantum phases. However, so far, how to detect these quantum phases effectively
remains an outstanding challenge. Here, we show that the optical Bragg
scattering of cold atoms loaded on optical lattices can be used to detect many
quantum phases which include not only the conventional superfluid and Mott
insulating phases, but also other important phases such as various kinds of
density waves (CDW), valence bond solids (VBS), CDW supersolids and VBS
supersolids.Comment: 4 pages, 3 colour figures, to appear in Phys. Rev. A, Rapid
Communicatio
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