Experimental Quantum Thermodynamics with Linear Optics

Zanin, G. L.; Häffner, Thomas; Talarico, Mara; Duzzioni, E. I.; Ribeiro, P. H. Souto; Landi, Gabriel T.; Céleri, Lucas C.

doi:10.1007/s13538-019-00700-6

Cited by 15 publications

(8 citation statements)

References 53 publications

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“…This indicates that there is in general an optimal nonzero amount of noise to maximize the efficiency of estimating the phase ξ from the control qubit of the switched channel. This is reminiscent of the phenomenon of stochastic resonance, which characterizes situations where maximum efficiency for information processing is obtained at a nonzero level of noise, and which in the quantum context assigns a beneficial role to decoherence [40,41,42,43,44,45,46], and relates at a broader level to nontrivial interactions among information, fluctuations and noise [47,48].…”

Section: For the Control Qubit Of The Switched Channelmentioning

confidence: 99%

Noisy quantum metrology with the assistance of indefinite causal order

Chapeau‐Blondeau

2021

Phys. Rev. A

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A generic qubit unitary operator affected by depolarizing noise is duplicated and inserted in a quantum switch process realizing a superposition of causal orders. The characterization of the resulting switched quantum channel is worked out for its action on the joint state of the probecontrol qubit pair. The switched channel is then specifically investigated for the important metrological task of phase estimation on the noisy unitary operator, with the performance assessed by the Fisher information, classical or quantum. A comparison is made with conventional techniques of estimation where the noisy unitary is directly probed in a one-stage or two-stage cascade with definite order, or several uses of them with two or more qubits. In the switched channel with indefinite order, specific properties are reported, meaningful for estimation and not present with conventional techniques. It is shown that the control qubit, although it never directly interacts with the unitary, can nevertheless be measured alone for effective estimation, while discarding the probe qubit that interacts with the unitary. Also, measurement of the control qubit maintains the possibility of efficient estimation in difficult conditions where conventional estimation becomes less efficient, as for instance with ill-configured input probes, or in blind situations when the axis of the unitary is unknown. Especially, effective estimation by measuring the control qubit remains possible even when the input probe tends to align with the axis of the unitary, or with a fully depolarized input probe, while in these conditions conventional estimation becomes inoperative. Measurement of the probe qubit of the switched channel is also analyzed and shown to add useful capabilities for phase estimation. The results contribute to the ongoing identification and analysis of the properties and capabilities of switched quantum channels with indefinite order for information processing, and uncover new possibilities for quantum estimation and qubit metrology.

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Section: For the Control Qubit Of The Switched Channelmentioning

confidence: 99%

Noisy quantum metrology with the assistance of indefinite causal order

Chapeau‐Blondeau

2021

Phys. Rev. A

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“…This protocol has been considered both theoretically [15,16,25] and experimentally [26][27][28][29][30][31][32] in distinct contexts within quantum thermodynamics. The probability distribution p m,n associated with the work is a central quantity in the discussed scheme.…”

Section: Statistical Workmentioning

confidence: 99%

Gauge invariant quantum thermodynamics: consequences for the first law

Céleri¹,

Rudnicki²

2021

Preprint

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“…This information is relevant for a macroscopic observer, however, it does not provide much information about the microscopic details of the occuring process. Recent developments in experimental techniques allow for manipulating and measuring systems at the nanoscale level [1][2][3][4][5][6]. In order to take full advantage of these techniques it is crucial to understand how thermodynamic laws translate into the non-equilibrium domain, where fluctuations of thermodynamic quantities begin to play a significant role and averaged quantities are no longer enough to characterize their thermodynamic behaviour.…”

Section: Introductionmentioning

confidence: 99%

Second law of thermodynamics for batteries with vacuum state

Lipka-Bartosik

Mazurek

Horodecki

2021

Quantum

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In stochastic thermodynamics work is a random variable whose average is bounded by the change in the free energy of the system. In most treatments, however, the work reservoir that absorbs this change is either tacitly assumed or modelled using unphysical systems with unbounded Hamiltonians (i.e. the ideal weight). In this work we describe the consequences of introducing the ground state of the battery and hence — of breaking its translational symmetry. The most striking consequence of this shift is the fact that the Jarzynski identity is replaced by a family of inequalities. Using these inequalities we obtain corrections to the second law of thermodynamics which vanish exponentially with the distance of the initial state of the battery to the bottom of its spectrum. Finally, we study an exemplary thermal operation which realizes the approximate Landauer erasure and demonstrate the consequences which arise when the ground state of the battery is explicitly introduced. In particular, we show that occupation of the vacuum state of any physical battery sets a lower bound on fluctuations of work, while batteries without vacuum state allow for fluctuation-free erasure.

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Experimental Quantum Thermodynamics with Linear Optics

Cited by 15 publications

References 53 publications

Noisy quantum metrology with the assistance of indefinite causal order

Noisy quantum metrology with the assistance of indefinite causal order

Gauge invariant quantum thermodynamics: consequences for the first law

Second law of thermodynamics for batteries with vacuum state

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