Changing quantum reference frames

Palmer, Matthew C.; Girelli, Florian; Bartlett, Stephen D.

doi:10.1103/physreva.89.052121

Cited by 57 publications

(68 citation statements)

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“…[26] it was shown that quantum mechanics can be consistently formulated without appealing to abstract reference frames of infinite mass. The subsequent literature [27][28][29][30][31][32][33][34] has then focused on different aspects of the introduction of quantum systems as reference frames, and mainly on a) the lack of a shared reference frame, b) bounded-size reference frames, and c) the possibility of overcoming general superselction rules by employing quantum reference frames (e.g., see [27] for a review). These approaches resort to an encoding of quantum information into relational degrees of freedom.…”

Section: Introductionmentioning

confidence: 99%

A change of perspective: switching quantum reference frames via a perspective-neutral framework

Vanrietvelde

Hoehn

Giacomini

et al. 2020

Quantum

118

247

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Treating reference frames fundamentally as quantum systems is inevitable in quantum gravity and also in quantum foundations once considering laboratories as physical systems. Both fields thereby face the question of how to describe physics relative to quantum reference systems and how the descriptions relative to different such choices are related. Here, we exploit a fruitful interplay of ideas from both fields to begin developing a unifying approach to transformations among quantum reference systems that ultimately aims at encompassing both quantum and gravitational physics. In particular, using a gravity inspired symmetry principle, which enforces physical observables to be relational and leads to an inherent redundancy in the description, we develop a perspectiveneutral structure, which contains all frame perspectives at once and via which they are changed. We show that taking the perspective of a specific frame amounts to a fixing of the symmetry related redundancies in both the classical and quantum theory and that changing perspective corresponds to a symmetry transformation. We implement this using the language of constrained systems, which naturally encodes symmetries. Within a simple one-dimensional model, we recover some of the quantum frame transformations of [1], embedding them in a perspective-neutral framework. Using them, we illustrate how entanglement and classicality of an observed system depend on the quantum frame perspective. Our operational language also inspires a new interpretation of Dirac and reduced quantized theories as perspective-neutral and perspectival quantum theories, respectively, and reveals the link between them. In this light, we suggest a new take on the relation between a 'quantum general covariance' and the diffeomorphism symmetry in quantum gravity. * p.hoehn@univie.ac.at arXiv:1809.00556v2 [quant-ph]

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Section: Introductionmentioning

confidence: 99%

A change of perspective: switching quantum reference frames via a perspective-neutral framework

Vanrietvelde

Hoehn

Giacomini

et al. 2020

Quantum

118

247

View full text Add to dashboard Cite

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“…The intended application of the results in this article, as well as one of the primary motivation for this investigation, is to study the act of changing quantum reference frames 6 . Palmer et al [18] have constructed an operational protocol for changing quantum reference frames associated with compact groups. They used the state G[ρ A ⊗ ρ S ] as a relational description of the state ρ S with respect to a quantum reference frame ρ A , and then considered the operation of changing the quantum reference frame from the state ρ A to ρ B .…”

Section: Discussionmentioning

confidence: 99%

Communicating without shared reference frames

Smith

2019

Phys. Rev. A

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We generalize a quantum communication protocol introduced by Bartlett et al. [New. J. Phys. 11, 063013 (2009)] in which two parties communicating do not share a classical reference frame, to the case where changes of their reference frames form a one-dimensional noncompact Lie group. Alice sends to Bob the state ρR ⊗ρS, where ρS is the state of the system Alice wishes to communicate and ρR is the state of an ancillary system serving as a token of her reference frame. Because Bob is ignorant of the relationship between his reference frame and Alice's, he will describe the state ρR ⊗ ρS as an average over all possible reference frames. Bob measures the reference token and applies a correction to the system Alice wished to communicate conditioned on the outcome of the measurement. The recovered state ρ S is decohered with respect to ρS, the amount of decoherence depending on the properties of the reference token ρR. We present an example of this protocol when Alice and Bob do not share a reference frame associated with the one-dimensional translation group and use the fidelity between ρS and ρ S to quantify the success of the recovery operation. arXiv:1812.08053v1 [quant-ph]

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“…However, in the framework of non-relativistic quantum information theory the problem of reference frames and of observers is very important [45,46] (see these papers and [47] for the relativistic extension), because for many tasks one needs information on clock synchronization, on the alignment of distinct Cartesian axes and on the determination of global positions. Connected problems are how two unrelated observers Alice and Bob can compare measures of spin when they do not share a common reference frame.…”

Section: Alice and Bob Quantum Observers?mentioning

confidence: 99%

“…In these cases the lack of a reference frame (or its level of imprecision [48]) is treated as a kind of decoherence (or quantum noise) which can wash out all the quantum features of a measurement. See [45,46] for an attempt to define quantum reference frames by quantizing the measuring apparatus associated with a mathematical observer (the previously quoted hybrid description).…”

Section: Alice and Bob Quantum Observers?mentioning

confidence: 99%

Non-inertial frames in Minkowski space-time, accelerated either mathematical or dynamical observers and comments on non-inertial relativistic quantum mechanics

Crater

Lusanna

2014

Int. J. Geom. Methods Mod. Phys.

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After a review of the existing theory of non-inertial frames and mathematical observers in Minkowski space-time we give the explicit expression of a family of such frames obtained from the inertial ones by means of point-dependent Lorentz transformations as suggested by the locality principle. These non-inertial frames have non-Euclidean 3-spaces and contain the differentially rotating ones in Euclidean 3-spaces as a subcase. Then we discuss how to replace mathematical accelerated observers with dynamical ones (their world-lines belong to interacting particles in an isolated system) and how to define Unruh-DeWitt detectors without using mathematical Rindler uniformly accelerated observers. Also some comments are done on the transition from relativistic classical mechanics to relativistic quantum mechanics in non-inertial frames.

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Changing quantum reference frames

Cited by 57 publications

References 57 publications

A change of perspective: switching quantum reference frames via a perspective-neutral framework

A change of perspective: switching quantum reference frames via a perspective-neutral framework

Communicating without shared reference frames

Non-inertial frames in Minkowski space-time, accelerated either mathematical or dynamical observers and comments on non-inertial relativistic quantum mechanics

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