Conserved Quantities and Measurements. (arXiv:2108.08342v1 [quant-ph])

2021年8月20日 星期五 下午3:42 | | | Edward J. Gillis | | | quant-ph updates on arXiv.org |

When a measurement is made on a system that is not in an eigenstate of the measured observable, it is often assumed that some conservation law has been violated. Discussions of the effect of measurements on conserved quantities often overlook the possibility of entanglement between the measured system and the preparation apparatus. The preparation of a system in any particular state necessarily involves interaction between the apparatus and the system. Since entanglement is a generic result of interaction, as shown by Gemmer and Mahler[1], and by Durt[2,3] one would expect some nonzero entanglement between apparatus and measured system, even though the amount of such entanglement is extremely small. Because the apparatus has an enormous number of degrees of freedom relative to the measured system, even a very tiny difference between the apparatus states that are correlated with the orthogonal states of the measured system can be sufficient to account for the perceived deviation from strict conservation of the quantity in question. Hence measurements need not violate conservation laws.

2021年8月20日 星期五 下午3:42 | | | Fabrizio Tamburini, Ignazio Licata | | | quant-ph updates on arXiv.org |

We propose a new thought experiment, based on present-day Quantum Information Technologies, to measure quantum gravitational effects through the Bose-Marletto-Vedral (BMV) effect by revealing the gravitational $t^3$ phase term, its expected relationships with low-energy quantum gravity phenomena and test the equivalence principle of general relativity. The technique here proposed promise to reveal gravitational field fluctuations from the analysis of the stochastic noise associated to an ideal output of a measurement process of a quantum system. To improve the sensitivity we propose to cumulate the effects of the gravitational field fluctuations in time on the outputs of a series of independent measurements acted on entangled states of particles, like in the building of a quantum cryptographic key, and extract from the associated time series the effect of the expected gravitational field fluctuations. In fact, an ideal quantum cryptographic key, built with the sharing of maximally entangled states of particles, is represented by a random sequence of uncorrelated symbols mathematically described by a perfect white noise, a stochastic process with zero mean and without correlation between its values taken at different times. Gravitational field perturbations, including quantum gravity fluctuations and gravitational waves, introduce additional phase terms that decohere the entangled pairs used to build the quantum cryptographic key, with the result of coloring the white noise. We find that this setup, built with massive mesoscopic particles, can potentially reveal the $t^3$ gravitational phase term and thus, the BMV effect.

Comment on `Relativistic wave-particle duality for spinors’. (arXiv:2103.04468v2 [gr-qc] UPDATED)

2021年8月20日 星期五 下午3:42 | | | Carl F. Diether, III, Joy Christian (Oxford) | | | quant-ph updates on arXiv.org |

In a recent paper [1], it has been proposed that relativistic wave-particle duality can be embodied in a relation that shows that the four-velocity of a particle is proportional to the Dirac four-current. In this note we bring out some problems with that idea. In particular, we point out that, in line with existing literature on Einstein-Cartan gravity with torsion, the spin-torsion term should represent negative energy. Moreover, if what is proposed in Eq. (20) of [1] is correct, then the spin torsion term would be zero in the rest frame of the fermion. We suggest a possible resolution of that dilemma.

2021年8月20日 星期五 下午3:42 | | | Du Xin-Dong, Long Chao-Yun | | | quant-ph updates on arXiv.org |

We first give a way which satisfies the bidirectional derivation between the generalized uncertainty principle and the corrected entropy of black holes. By this way, the generalized uncertainty principle can be indirectly modified by some correction elements which are carrried by the corrected entropy. Then we put an entropy modified by quantum tunneling into the way, from which we get a new generalized uncertainty principle, and finally find the new one has a broader form and a stronger adaptability to the sign of parameter.

2021年8月20日 星期五 下午3:42 | | | gr-qc updates on arXiv.org |

Authors: Fabrizio Corelli, Taishi Ikeda, Paolo Pani

We perform extensive nonlinear numerical simulations of the spherical collapse of (charged) wavepackets onto a charged black hole within Einstein-Maxwell theory and in Einstein-Maxwell-scalar theory featuring nonminimal couplings and a spontaneous scalarization mechanism. We confirm that black holes in full-fledged Einstein-Maxwell theory cannot be overcharged past extremality and no naked singularities form, in agreement with the cosmic censorship conjecture. We show that naked singularities do not form even in Einstein-Maxwell-scalar theory, although it is possible to form scalarized black holes with charge above the Reissner-Nordstr\”om bound. We argue that charge and mass extraction due to superradiance at fully nonlinear level is crucial to bound the charge-to-mass ratio of the final black hole below extremality. We also discuss some “descalarization” mechanisms for scalarized black holes induced either by superradiance or by absorption of an opposite-charged wavepacket; in all cases the final state after descalarization is a subextremal Reissner-Nordstr\”om black hole.

2021年8月20日 星期五 上午1:53 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Stoica, Ovidiu Cristinel (2021) World Theory. [Preprint]

Generation of optical Schrödinger cat states in intense laser–matter interactions

2021年8月19日 星期四 上午8:00 | | | P. Tzallas | | | Nature Physics – Issue – nature.com science feeds |

Nature Physics, Published online: 19 August 2021; doi:10.1038/s41567-021-01317-w

Schrödinger cat states are observed in intense laser–atom interactions. These are a superposition of the initial state of the laser and the coherent state that results from the interaction between the light and atoms.

Relational physics and the concept of continuity.

2021年8月19日 星期四 上午6:18 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Prokopov, Aleksey (2021) Relational physics and the concept of continuity. [Preprint]

Experimental Detection of the Correlation Rényi Entropy in the Central Spin Model

2021年8月18日 星期三 下午6:00 | | | Mohamad Niknam, Lea F. Santos, and David G. Cory | | | PRL: General Physics: Statistical and Quantum Mechanics, Quantum Information, etc. |

Author(s): Mohamad Niknam, Lea F. Santos, and David G. Cory

We propose and experimentally measure an entropy that quantifies the volume of correlations among qubits. The experiment is carried out on a nearly isolated quantum system composed of a central spin coupled and initially uncorrelated with 15 other spins. Because of the spin-spin interactions, inform…

[Phys. Rev. Lett. 127, 080401] Published Wed Aug 18, 2021

An algebraic approach to physical fields

2021年8月18日 星期三 下午2:59 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Chen, Lu and Fritz, Tobias (2021) An algebraic approach to physical fields. [Preprint]

Problems of empirical solutions to the theory-ladenness of observation

2021年8月18日 星期三 上午8:00 | | | Latest Results for Synthese |

**Abstract**

Recent years have seen enticing empirical approaches to solving the epistemological problem of the theory-ladenness of observation. I group these approaches in two categories according to their method of choice: testing and refereeing. I argue that none deliver what friends of theory-neutrality want them to. Testing does not work because both evidence from cognitive neuroscience and perceptual pluralism independently invalidate the existence of a common observation core. Refereeing does not work because it treats theory-ladenness as a kind of superficial, removable bias. Even if such treatment is plausible, there is likely no method to ascertain that effects of this bias are not present. More importantly, evidence from cognitive neuroscience suggests that a deeper, likely irremovable kind of theory-ladenness lies within the perceptual modules.

What Breathers Fire into the Equations

2021年8月16日 星期一 下午3:44 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Loewer, Barry (2021) What Breathers Fire into the Equations. UNSPECIFIED.

Time’s Arrow Points to Many Worlds

2021年8月16日 星期一 下午3:42 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Gao, Shan (2021) Time’s Arrow Points to Many Worlds. [Preprint]

Indeterministic finite-precision physics and intuitionistic mathematics

2021年8月16日 星期一 上午4:23 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

van der Lugt, Tein (2020) Indeterministic finite-precision physics and intuitionistic mathematics. [Preprint]