Many-body state engineering using measurements and fixed unitary dynamics

Pedersen, Mads Kock; Sørensen, Jens Jakob; Tichy, Malte C.; Sherson, Jacob

doi:10.1088/1367-2630/16/11/113038

Cited by 41 publications

(48 citation statements)

References 30 publications

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“…In the above the Markov approximation is implied in the limit when T=0 [60,61].This allows to consider the effect of measurement back-action, the role of local processes and their interplay due to light-induced non-local interactions simultaneously. This opens a new venue for exploration regarding the design of global structured dissipation channels and measurement induced projection and state design of non-trivial quantum correlated states [50][51][52], as well as, control [45,46] and the transition to classicality [64]. As it has been shown, this can greatly enhance and optimise the desired quantum properties of light by design.…”

Section: Effective Master Equationmentioning

confidence: 99%

Quantum properties of light scattered from structured many-body phases of ultracold atoms in quantum optical lattices

Caballero-Benítez

Mekhov

2015

New J. Phys.

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Quantum trapping potentials for ultracold gases change the landscape of classical properties of scattered light and matter. The atoms in a quantum many-body correlated phase of matter change the properties of light and vice versa. The properties of both light and matter can be tuned by design and depend on the interplay between long-range (nonlocal) interactions mediated by an optical cavity and short-range processes of the atoms. Moreover, the quantum properties of light get significantly altered by this interplay, leading the light to have nonclassical features. Further, these nonclassical features can be designed and optimised. OPEN ACCESS RECEIVED), we find that the matter induces structure to the squeezing parameter. As it has been shown [24] besides from SF, MI the system supports gapped superfluid states, dimer phases, supersolid (SS) and density waves (DW). 6.2. Diagonal coupling, illuminating at lattice sites. Without bond ordering (J 0 B, = j , J J D, D

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Section: Effective Master Equationmentioning

confidence: 99%

Quantum properties of light scattered from structured many-body phases of ultracold atoms in quantum optical lattices

Caballero-Benítez

Mekhov

2015

New J. Phys.

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“…Projective measurements are essential elements of quantum technologies, for example for teleportation [24], measurement-based quantum computation [25], entangling macroscopic atomic ensembles [26], many-body state engineering [27] or entanglement generation between superconducting qubits within a meter of distance [28]. In particular, for cold atoms in optical lattices, nondemolition quantum measurements have been proposed for the creation and the detection of spin-spin correlations [29].…”

Section: Introductionmentioning

confidence: 99%

Measurement-assisted quantum communication in spin channels with dephasing

Bayat

Omar

2015

New J. Phys.

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We propose a protocol for countering the effects of dephasing in quantum state transfer over a noisy spin channel weakly coupled to the sender and receiver qubits. Our protocol, based on performing regular global measurements on the channel, significantly suppresses the nocuous environmental effects and offers much higher fidelities than the traditional no-measurement approach. Our proposal can also operate as a robust two-qubit entangling gate over distant spins. Our scheme counters any source of dephasing, including those for which the well established dynamical decoupling approach fails. Our protocol is probabilistic, given the intrinsic randomness in quantum measurements, but its success probability can be maximized by adequately tuning the rate of the measurements. A Bayat and Y Omar J J. ¢  In this limit, α diverges as J J ¢ and, by using a simple algebra, one can show that p J J Jt lim 1 4 sin 2 . 2 3 0 1 2 2 2 J J

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“…They also naturally appear in open quantum systems [10,11] and are connected to the study of non-equilibrium thermodynamics and non-equilibrium quantum phase transitions [12]. It has been pointed out that engineering open quantum systems can induce a phase space dynamics which drives the quantum system in a pure state by solely dissipative means [13][14][15][16]. Controlling and understanding the non-equilibrium steady-states of an open many-body quantum system therefore offers new routes for quantum state engineering and out-of-equilibrium quantum dynamics.…”

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confidence: 99%

Bistability in a Driven-Dissipative Superfluid

et al. 2016

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We experimentally study a driven-dissipative Josephson junction array, realized with a weakly interacting Bose Einstein condensate residing in a one-dimensional optical lattice. Engineered losses on one site act as a local dissipative process, while tunneling from the neighboring sites constitutes the driving force. We characterize the emerging steady-states of this atomtronic device. With increasing dissipation strength γ the system crosses from a superfluid state, characterized by a coherent Josephson current into the lossy site to a resistive state, characterized by an incoherent hopping transport. For intermediate values of γ, the system exhibits bistability, where a superfluid and a resistive branch coexist. We also study the relaxation dynamics towards the steady-state, where we find a critical slowing down, indicating the presence of a non-equilibrium phase transition.PACS numbers: 03.75. Lm, 74.40.Gh, 03.65.Yz, 42.50.Dv Non-equilibrium steady-states constitute fix points of the phase space dynamics of classical and quantum systems [1][2][3]. They emerge under the presence of a driving force and lie at the heart of transport phenomena such as heat conduction [4][5][6] or current flow [7][8][9]. They also naturally appear in open quantum systems [10,11] and are connected to the study of non-equilibrium thermodynamics and non-equilibrium quantum phase transitions [12]. It has been pointed out that engineering open quantum systems can induce a phase space dynamics which drives the quantum system in a pure state by solely dissipative means [13][14][15][16]. Controlling and understanding the non-equilibrium steady-states of an open many-body quantum system therefore offers new routes for quantum state engineering and out-of-equilibrium quantum dynamics. Here, we investigate the steady-states of a driven-dissipative Josephson junction array realized with a Bose-Einstein condensate in a one-dimensional optical lattice [17]. Varying the strength of the dissipation, the system can be tuned from superfluid to resistive transport. In between, it exhibits a region of bistability. The peculiar transport properties make such devices promising elements for complex atomtronic circuits. At the same time, they are an interesting candidate to study generic properties of an open quantum system. Our results manifest the high potential of open system control in ultracold quantum gases.Open quantum systems are characterized by the competition between the intrinsic unitary dynamics, governed by the Hamilton operator H, and the coupling to the environment, which induces non-unitary time evolution and quantum jumps, described by jump operators (â i ,â i † ) which act on the system with rates γ i [10]. The time evolution of the density matrix ρ in Markov approximation is then described by a master equation in Lindblad form [18]:FIG. 1. Schematics of the experiment. One site of an array of superfluids is subject to an incoherent local loss process with rate γ. The coherent tunneling coupling between the reservoir sites is given b...

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Many-body state engineering using measurements and fixed unitary dynamics

Cited by 41 publications

References 30 publications

Quantum properties of light scattered from structured many-body phases of ultracold atoms in quantum optical lattices

Quantum properties of light scattered from structured many-body phases of ultracold atoms in quantum optical lattices

Measurement-assisted quantum communication in spin channels with dephasing

Bistability in a Driven-Dissipative Superfluid

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