Physics within a quantum reference frame

Angelo, R. M.; Brunner, Nicolás; Popescu, Sandu; Short, Anthony; Skrzypczyk, Paul

doi:10.1088/1751-8113/44/14/145304

Cited by 84 publications

(133 citation statements)

References 25 publications

(54 reference statements)

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“…As an example, also investigated in [38,39], consider a particle S in one dimension, with position defined relative to a reference frame consisting of another particle A which provides an origin. Introduce a second particle, B, which we would like to use as a new reference frame for S. Classically, this seems straightforward: the position of S described in terms of B will differ by the relative position of the two reference frames, x B − x A .…”

Section: Change Of a Quantum Reference Framementioning

confidence: 99%

Changing quantum reference frames

2014

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We consider the process of changing reference frames in the case where the reference frames are quantum systems. We find that, as part of this process, decoherence is necessarily induced on any quantum system described relative to these frames. We explore this process with examples involving reference frames for phase and orientation. Quantifying the effect of changing quantum reference frames provides a theoretical description for this process in quantum experiments, and serves as a first step in developing a relativity principle for theories in which all objects including reference frames are necessarily quantum.

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Section: Change Of a Quantum Reference Framementioning

confidence: 99%

Changing quantum reference frames

2014

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“…In recent years, such a treatment of reference frames in quantum theory, i.e. as quantum objects has led to the formalism of 'QRF' [4,8]. A QRF is different from its classical counterpart in two ways.…”

Section: Introductionmentioning

confidence: 99%

Quantum parameter estimation with imperfect reference frames

2015

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Quantum metrology studies quantum strategies which enable us to outperform their classical counterparts. In this framework, the existence of perfect classical reference frames is usually assumed. However, such ideal reference frames might not always be available. The reference frames required in metrology strategies can either degrade or become misaligned during the estimation process. We investigate how the imperfectness of reference frames leads to noise which in general affects the ultimate precision limits in measurement of physical parameters. Moreover, since quantum parameter estimation can be phrased as a quantum communication protocol between two parties, our results provide deeper insight into quantum communication protocols with misaligned reference frames. Our framework allows for the study of noise on the efficiency of such schemes.2 system or a quantum harmonic oscillator as carrier of her message. The message can be encoded as a phase parameter in the state of the spin − 1 2 particle or in the state of the quantum harmonic oscillator. Bob then performs a measurement on the system in order to decode the message, i.e. the encoded phase parameter. The quality of this communication protocol can be improved by optimization of both stages of the protocol, namely Alice's encoding process and Bob's decoding process. However, standard approaches to quantum communication, such as encoding qubits into polarization degree of freedom of photons, require that all parties have knowledge of a shared reference frame. This means that in the absence of such knowledge, the involved parties need to initially establish aligned reference frames. Despite the considerable amount of progress in the development of protocols for aligning reference frames such as clock synchronization and Cartesian frame alignment [4], maintaining aligned reference frames is still a large obstacle in achieving such tasks. For instance when the

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“…In this approximation, the NLSM becomes quadratic in X, each component decouples to others and enters independently in Eq. (10). Notice that λ has dimension [mass]…”

Section: A Renormalizationmentioning

confidence: 99%

The Cosmological Constant Problem and Quantum Spacetime Reference Frame

Luo¹

2017

Preprint

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We generalize the idea of quantum clock time to quantum spacetime reference frame via physical realization of a reference system by quantum rulers and clocks. Omitting the internal degrees of freedom (such as spins) of the physical rulers and clocks, only considering their metric properties, the spacetime reference frame is described by a bosonic non-linear sigma model. We study the quantum behavior of the system under approximations, and obtain (1) a cosmological constant valued (2/π)ρc0 (ρc0 the critical density at near current epoch) which is very close to the observations; (2) an effective Einstein-Hilbert term in the effective action; (3) the ratio of variance to mean-squared of spacetime interval tends to a universal constant 2/π in the infrared region. This effect is testable by observing a linear dependence between the inherent quantum variance and mean-squared of the redshifts from cosmic distant spectral lines. The proportionality is expected to be the observed percentage of the dark energy. We also generalize the equivalence principle to be valid for all quantum phenomenon.

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Physics within a quantum reference frame

Cited by 84 publications

References 25 publications

Changing quantum reference frames

Changing quantum reference frames

Quantum parameter estimation with imperfect reference frames

The Cosmological Constant Problem and Quantum Spacetime Reference Frame

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