TY  - JOUR
A1  - Mari, A.
A1  - Eisert, J.
T1  - Cooling by Heating: Very Hot Thermal Light Can Significantly Cool
 Quantum Systems
JF  - PHYSICAL REVIEW LETTERS
N2  - We introduce the idea of actually cooling quantum systems by means of incoherent thermal light, hence giving rise to a counterintuitive mechanism of "cooling by heating." In this effect, the mere incoherent occupation of a quantum mechanical mode serves as a trigger to enhance the coupling between other modes. This notion of effectively rendering states more coherent by driving with incoherent thermal quantum noise is applied here to the optomechanical setting, where this effect occurs most naturally. We discuss two ways of describing this situation, one of them making use of stochastic sampling of Gaussian quantum states with respect to stationary classical stochastic processes. The potential of experimentally demonstrating this counterintuitive effect in optomechanical systems with present technology is sketched.
Y1  - 2012
U6  - https://doi.org/10.1103/PhysRevLett.108.120602
SN  - 0031-9007
VL  - 108
IS  - 12
PB  - AMER PHYSICAL SOC
CY  - COLLEGE PK
ER  - 
TY  - JOUR
A1  - Trotzky, S.
A1  - Chen, Y-A.
A1  - Flesch, A.
A1  - McCulloch, I. P.
A1  - Schollwöck, U.
A1  - Eisert, J.
A1  - Bloch, I.
T1  - Probing the relaxation towards equilibrium in an isolated strongly correlated one-dimensional Bose gas
JF  - Nature physics
N2  - The problem of how complex quantum systems eventually come to rest lies at the heart of statistical mechanics. The maximum-entropy principle describes which quantum states can be expected in equilibrium, but not how closed quantum many-body systems dynamically equilibrate. Here, we report the experimental observation of the non-equilibrium dynamics of a density wave of ultracold bosonic atoms in an optical lattice in the regime of strong correlations. Using an optical superlattice, we follow its dynamics in terms of quasi-local densities, currents and coherences-all showing a fast relaxation towards equilibrium values. Numerical calculations based on matrix-product states are in an excellent quantitative agreement with the experimental data. The system fulfills the promise of being a dynamical quantum simulator, in that the controlled dynamics runs for longer times than present classical algorithms can keep track of.
Y1  - 2012
U6  - https://doi.org/10.1038/NPHYS2232
SN  - 1745-2473
VL  - 8
IS  - 4
SP  - 325
EP  - 330
PB  - Nature Publ. Group
CY  - London
ER  - 
TY  - JOUR
A1  - Ohliger, M.
A1  - Eisert, J.
T1  - Efficient measurement-based quantum computing with continuous-variable systems
JF  - Physical review : A, Atomic, molecular, and optical physics
N2  - We present strictly efficient schemes for scalable measurement-based quantum computing using continuous-variable systems: These schemes are based on suitable non-Gaussian resource states, ones that can be prepared using interactions of light with matter systems or even purely optically. Merely Gaussian measurements such as optical homodyning as well as photon counting measurements are required, on individual sites. These schemes overcome limitations posed by Gaussian cluster states, which are known not to be universal for quantum computations of unbounded length, unless one is willing to scale the degree of squeezing with the total system size. We establish a framework derived from tensor networks and matrix product states with infinite physical dimension and finite auxiliary dimension general enough to provide a framework for such schemes. Since in the discussed schemes the logical encoding is finite dimensional, tools of error correction are applicable. We also identify some further limitations for any continuous-variable computing scheme from which one can argue that no substantially easier ways of continuous-variable measurement-based computing than the presented one can exist.
Y1  - 2012
U6  - https://doi.org/10.1103/PhysRevA.85.062318
SN  - 1050-2947
VL  - 85
IS  - 6
PB  - American Physical Society
CY  - College Park
ER  - 
TY  - JOUR
A1  - Mari, A.
A1  - Eisert, J.
T1  - Opto- and electro-mechanical entanglement improved by modulation
JF  - New journal of physics : the open-access journal for physics
N2  - One of the main milestones in the study of opto- and electromechanical systems is to certify entanglement between a mechanical resonator and an optical or microwave mode of a cavity field. In this work, we show how a suitable time-periodic modulation can help to achieve large degrees of entanglement, building upon the framework introduced in Mari and Eisert (2009 Phys. Rev. Lett. 103 213603). It is demonstrated that with suitable driving, the maximum degree of entanglement can be significantly enhanced, in a way exhibiting a nontrivial dependence on the specifics of the modulation. Such time-dependent driving might help to experimentally achieve entangled mechanical systems also in situations when quantum correlations are otherwise suppressed by thermal noise.
Y1  - 2012
U6  - https://doi.org/10.1088/1367-2630/14/7/075014
SN  - 1367-2630
VL  - 14
PB  - IOP Publ. Ltd.
CY  - Bristol
ER  -