Quantum states and phases in driven open quantum systems with cold atoms

Diehl, Sebastian; Micheli, A.; Kantian, Adrian; Kraus, Barbara; Büchler, Hans Peter; Zoller, P.

doi:10.1038/nphys1073

Cited by 1,132 publications

(1,292 citation statements)

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“…This could be achieved by modifying the properties of the reservoir to form a bound state and to approach the non-Markovian regime via the potential usage of reservoir engineering [21][22][23]. Many experimental platforms (e.g., mesoscopic ion traps [21], cold atom BECs [22], and the photonic crystal materials [14] have exhibited the controllability of decoherence behavior of relevant quantum systems through optimally designing the size (i.e., modifying the spectrum) of the reservoir and/or the coupling strength between the system and the reservoir. It is also worth mentioning that a proposal aimed at simulating the spin-Boson model, which is relevant to the one considered in this paper, has been reported in a trapped ion system [24].…”

Section: Conclusion and Discussionmentioning

confidence: 99%

Mechanism of entanglement preservation

et al. 2010

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We study the entanglement preservation of two qubits locally interacting with their reservoirs. We show that the existence of a bound state of the qubit and its reservoir and the non-Markovian effect are two essential ingredients and their interplay plays a crucial role in preserving the entanglement in the steady state. When the non-Markovian effect is neglected, the entanglement sudden death (ESD) is reproduced. On the other hand, when the non-Markovian is significantly strong but the bound state is absent, the phenomenon of the ESD and its revival is recovered. Our formulation presents a unified picture about the entanglement preservation and provides a clear clue on how to preserve the entanglement in quantum information processing.

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Section: Conclusion and Discussionmentioning

confidence: 99%

Mechanism of entanglement preservation

et al. 2010

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“…The quantum state engineering based on the dynamics in the open quantum systems [13], in particular in the optical lattices [14], is a well-known idea. As distinct from the previous proposal of the quantum state engineering in the optical lattices (see also the recent study [15]), where the inter-site atomic currents are coupled to reservoirs, in our case the dissipation acts locally and incoherently on a periodic sublattice of the lattice sites, whereas the condensate is driven to a non-local coherent state.…”

Section: Introductionmentioning

confidence: 99%

State engineering for a Bose-Einstein condensate in an optical lattice by means of a periodic sublattice of dissipative sites

Shchesnovich

2012

Phys. Rev. A

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We introduce the notion of dissipative periodic lattice as an optical lattice with periodically distributed dissipative sites and argue that it allows to engineer unconventional Bose-Einstein superfluids with the complex-valued order parameter. We consider two examples, the one-dimensional dissipative optical lattice, where each third site is dissipative, and the dissipative honeycomb optical lattice, where each dissipative lattice site neighbors three non-dissipated sites. The tight-binding approximation is employed, which allows one to obtain analytical results. In the one-dimensional case the condensate is driven to a coherent Bloch-like state with non-zero quasimomentum, which breaks the translational periodicity of the dissipative lattice. In the two-dimensional case the condensate is driven to a zero quasimomentum Bloch-like state, which is a coherent superposition of four-site discrete vortices of alternating vorticity with the vortex centers located at the dissipative sites.

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“…For the interaction-dominated regime this increase is logarithmic, whereas it is a power law in the tunneling-dominated regime. Nonetheless, for any non-vanishing cavity decay rate, the correlation length always remains finite.Related questions are of high relevance for ultra-cold atoms [24], ions [25] , superconducting circuits [26] or exciton-polariton condensates [7]. For the latter, functional renormalization group approaches showed that, arXiv:1401.5776v2 [quant-ph]…”

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confidence: 99%

“…Related questions are of high relevance for ultra-cold atoms [24], ions [25] , superconducting circuits [26] or exciton-polariton condensates [7]. For the latter, functional renormalization group approaches showed that, arXiv:1401.5776v2 [quant-ph]…”

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Spontaneous collective coherence in driven dissipative cavity arrays

Ruiz-Rivas¹,

Valle²,

Gies³

et al. 2014

Phys. Rev. A

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We study an array of dissipative tunnel-coupled cavities, each interacting with an incoherently pumped two-level emitter. For cavities in the lasing regime, we find correlations between the light fields of distant cavities, despite the dissipation and the incoherent nature of the pumping mechanism. These correlations decay exponentially with distance for arrays in any dimension but become increasingly long ranged with increasing photon tunneling between adjacent cavities. The interaction-dominated and the tunneling-dominated regimes show markedly different scaling of the correlation length which always remains finite due to the finite photon trapping time. We propose a series of observables to characterize the spontaneous build-up of collective coherence in the system. Arrays of optical or microwave cavities, each interacting strongly with quantum emitters and mutually coupled via the exchange of photons, have been introduced as prototype setups for the study of quantum manybody physics of light [1][2][3]. Even though ground or thermal equilibrium states of the corresponding quantum many-body systems are challenging to generate in experiments, much of the initial attention has focussed on this regime [4][5][6][7]. In any realistic experiment with cavity arrays, however, photons are dissipated due to the imperfect confinement of the light, and emitter excitations have finite lifetimes. It is thus crucial and useful to explore the driven-dissipative regime of these structures, where photon losses are continuously compensated by pumping new photons into the cavities. A special role is here taken by the stationary states where photon pumping and losses balance each other in a dynamical equilibrium. This regime has thus received considerable attention in recent years, where coherent and strongly correlated phases have been discovered [8][9][10], but also analogies to quantum Hall physics [11] and topologically protected quantum states [12] have been discussed.In previous investigations of coupled cavity arrays in driven-dissipative regimes, the pump mechanism that injects photons into the array has been assumed to be a coherent drive at each cavity [8][9][10][11][12]. Therefore any phase-coherence between light fields in distant cavities that was seen in these studies can at least in part be attributed to the fixed phase relation between their coherent input drives. Here, in contrast, we show that such a coherence between distant cavities can build up spontaneously, triggered only by physical processes within the array. In this way we address the question of whether a non-equilibrium superfluid can develop in these structures. To this end, we consider a cavity array that is only driven by an incoherent pump which explicitly avoids any external source for a preferred phase relation between photons in different cavities.In our model, each cavity strongly interacts with a twolevel emitter. Whereas both, emitters and cavity photons, are subject to dissipation processes, the cavities are excited via the emitters only, whi...

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Quantum states and phases in driven open quantum systems with cold atoms

Cited by 1,132 publications

References 32 publications

Mechanism of entanglement preservation

Mechanism of entanglement preservation

State engineering for a Bose-Einstein condensate in an optical lattice by means of a periodic sublattice of dissipative sites

Spontaneous collective coherence in driven dissipative cavity arrays

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