Qubit-assisted thermometry of a quantum harmonic oscillator

Brunelli, Matteo; Olivares, Stefano; Paternostro, Mauro; Paris, Matteo G. A.

doi:10.1103/physreva.86.012125

Cited by 89 publications

(84 citation statements)

References 29 publications

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“…The qubit-oscillator coupling shown in Eq. (16) (and its limit under rotating-wave approximation) has already been addressed concerning the estimation of the temperature of a mechanical resonator in thermal equilibrium, and the optimality of energy measurements performed on the qubit to this purpose has been shown [38,39]. This motivates the choice of that specific form of interaction, given that according to Eq.…”

Section: Hybrid Optomechanics For Discrete-variable Probingmentioning

confidence: 99%

“…Finally, we assume that no initial correlations are present between the two systems. This can be justified by assuming the optomechanical interaction to be strong enough to quickly prepare the mechanical initial state, which is then coupled to the two-level system through a slow (adiabatic) Hamiltonian [37,39]. The measurements are performed on the reduced state of the probeˆ q after its joint evolution with the mechanical mode, which is obtained aŝ…”

Section: Hybrid Optomechanics For Discrete-variable Probingmentioning

confidence: 99%

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Quantum-limited estimation of continuous spontaneous localization

et al. 2017

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We apply the formalism of quantum estimation theory to extract information about potential collapse mechanisms of the continuous spontaneous localisation (CSL) form. In order to estimate the strength with which the field responsible for the CSL mechanism couples to massive systems, we consider the optomechanical interaction between a mechanical resonator and a cavity field. Our estimation strategy passes through the probing of either the state of the oscillator or that of the electromagnetic field that drives its motion. In particular, we concentrate on all-optical measurements, such as homodyne and heterodyne measurements. We also compare the performances of such strategies with those of a spin-assisted optomechanical system, where the estimation of the CSL parameter is performed through time-gated spin-like measurements.Understanding the nature of the quantum-to-classical (QtC) transition is a long-sought problem that attracts an evergrowing attention [1][2][3][4][5][6]. While quantum mechanics has undergone exhaustive and extremely successful testings in the microscopic realm, the apparent absence of quantum manifestations at the macroscopic scale cries for a deeper understanding. In particular, this lack of evidence reinforces the need of assessing the causes for the emergence of classical mechanics from fundamental quantum evolution. The most widely accepted theory behind such process is quantum decoherence [6]: The environment surrounding any quantum system monitors its state continuously, practically collapsing the system's wavefunction and curtailing any quantum behaviour. Such process is conjectured to occur more quickly with the growing size of the system at hand. Under this regime, macroscopic superpositions would be possible in macroscopic systems perfectly isolated from their environment, a condition that is, for all practical purposes, not realisable.However, a set of theories, usually referred to as collapse models (CMs), suggests an alternative route to the explanation of the QtC transition by putting forward fundamental underlying mechanisms responsible for the collapse of the wavefunction [7]. The strength of this effect should increase with the size (mass) of the system, leaving microscopic (macroscopic) systems fully within the quantum (classical) realm. The key difference between CMs and standard quantum mechanics is that in the framework entailed by the former, perfectly isolated macroscopic objects would continue to act classically.Among the proposals put forward so far to test (or rule out) some of the currently formulated CMs [8][9][10], those based on the experimental platform of cavity optomechanics offer features of undemanding scalability of the mass of the system to be probed and high-sensitivity of measurement. Most remarkably, at variance with standardly pursued approaches [11], they bypass the need for the construction and quantum-limited management of large interferometers [12,13]. notwithstanding such promising features, the investigation of CMs still poses considerable experim...

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Section: Hybrid Optomechanics For Discrete-variable Probingmentioning

confidence: 99%

Section: Hybrid Optomechanics For Discrete-variable Probingmentioning

confidence: 99%

Quantum-limited estimation of continuous spontaneous localization

et al. 2017

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“…With the progress in manipulation of individual quantum system, the study of thermometry precision, using individual quantum system as a probe, has attracted considerable attentions [16][17][18][19][20][21][22]. Specifically, Ref.…”

Section: Introductionmentioning

confidence: 99%

“…[16] analyzed the thermometry of an unknown bath and proved that the optimal quantum probe is an effective twolevel atom with a maximally degenerate excited state, while Refs. [17,18] used a single qubit as the probe to estimate the temperature of the micro-mechanical resonators. Meanwhile, Jevtic et al [19] have also used a single qubit to distinguish between two different temperatures of a bosonic bath and found the potential role * zoujian@bit.edu.cn played by coherence and entanglement in simple thermometric tasks.…”

Section: Introductionmentioning

confidence: 99%

Improved thermometry of low-temperature quantum systems by a ring-structure probe

Guo

Zou

et al. 2015

Phys. Rev. A

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The thermometry precision of a sample is a question of both fundamental and technological importance. In this paper, we consider a ring-structure system as our probe to estimate the temperature of a bath. Based on the Markovian master equation of the probe, we calculate the quantum Fisher information (QFI) of the probe at any time. We find that for the thermal equilibrium thermometry, the ferromagnetic structure can measure a lower temperature of the bath with a higher precision compared with the non-structure probe. While for the dynamical thermometry, the antiferromagnetic structure can make the QFI of the probe in the dynamical process much larger than that in equilibrium with the bath, which is somewhat counterintuitive. Moreover, the best accuracy for the thermometry achieved in the antiferromagnetic structure case can be much higher than that in the non-structure case. The physical mechanisms of above phenomena are given in this paper.

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“…This happens for several quantities of interest in quantum technology and in all these cases, quantum estimation theory [15][16][17] provides tools to evaluate the ultimate precision attainable by any estimation procedure and to design optimal measurement schemes. Examples include the estimation of the phase [18][19][20][21], quantum correlations [22][23][24], temperature [25,26], characterization of classical processes or environmental parameters [27][28][29][30], and, indeed, the coupling constants of different kinds of interactions [31][32][33][34][35].…”

Section: Introductionmentioning

confidence: 99%

Characterization of qubit chains by Feynman probes

et al. 2016

Self Cite

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We address the characterization of qubit chains and assess the performances of local measurements compared to those provided by Feynman probes, i.e. nonlocal measurements realized by coupling a single qubit register to the chain. We show that local measurements are suitable to estimate small values of the coupling and that a Bayesian strategy may be successfully exploited to achieve optimal precision. For larger values of the coupling Bayesian local strategies do not lead to a consistent estimate. In this regime, Feynman probes may be exploited to build a consistent Bayesian estimator that saturates the Cramér-Rao bound, thus providing an effective characterization of the chain. Finally, we show that ultimate bounds to precision, i.e. saturation of the quantum Cramér-Rao bound, may be achieved by a two-step scheme employing Feynman probes followed by local measurements.

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Qubit-assisted thermometry of a quantum harmonic oscillator

Cited by 89 publications

References 29 publications

Quantum-limited estimation of continuous spontaneous localization

Quantum-limited estimation of continuous spontaneous localization

Improved thermometry of low-temperature quantum systems by a ring-structure probe

Characterization of qubit chains by Feynman probes

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