Simultaneity in wavepacket reduction

Picturing wavepacket reduction

A coherent picture of the wavepacket-reduction process is proposed which is formulated in the framework of a deterministic and realist interpretation where the concepts of knowledge or information and of point particles do not appear. It is shown how the picture accounts for the experiments on interaction-free and delayed-choice measurements and those on interference with partial absorption.

Reduction of the Wavepacket: How Long Does it Take?

We show that the ``reduction of the wavepacket'' caused by the interaction with the environment occurs on a timescale which is typically many orders of magnitude shorter than the relaxation timescale $τ$. In particular, we show that in a system interacting with a ``canonical'' heat bath of harmonic oscillators decorrelation timescale of two pieces of the wave-packet separated by $N$ thermal de Broglie wavelengths is approximately $τ/N^2$. Therefore, in the classical limit $\hbar \to 0$ dynamical reversibility $(τ\to \infty)$ is compatible with ``instantaneous'' coherence loss.

A conjecture concerning determinism, reduction, and measurement in quantum mechanics

Determinism is established in quantum mechanics by tracing the probabilities in the Born rules back to the absolute (overall) phase constants of the wave functions and recognizing these phase constants as pseudorandom numbers. The reduction process (collapse) is independent of measurement. It occurs when two wavepackets overlap in ordinary space and satisfy a certain criterion, which depends on the phase constants of both wavepackets. Reduction means contraction of the wavepackets to the place of overlap. The measurement apparatus fans out the incoming wavepacket into spatially separated eigen…

WavePacket：用于量子动力学数值模拟的Matlab包。II：开放量子系统、最优控制和模型降维

WavePacket: A Matlab package for numerical quantum dynamics. II: Open quantum systems, optimal control, and model reduction

本文介绍了WavePacket包在开放量子系统、最优控制和模型降维方面的应用，通过引入Lindblad算子模拟耗散和退相位，以及基于可控性和可观测性Gramians的平衡变换进行状态降维，同时利用H2最优模型降维技术减少维度。

Nonclassicality and entanglement for wavepackets

Mode-entanglement based criteria and measures become insufficient for broadband emission, e.g. from spasers (plasmonic nano-lasers). We introduce criteria and measures for the (i) total entanglement of two wavepackets, (ii) entanglement of a wavepacket with an ensemble and (iii) total nonclassicality of a wavepacket~(WP). We discuss these criteria in the context of (i) entanglement of two WPs emitted from two initially entangled cavities (or two initially entangled atoms) and (ii) entanglement of an emitted WP with the ensemble/atom for the spontaneous emission and the single-photon superradia…

Spin-motion entanglement and state diagnosis with squeezed oscillator wavepackets

Mesoscopic superpositions of distinguishable coherent states provide an analog to the Schrödinger's cat thought experiment. For mechanical oscillators these have primarily been realised using coherent wavepackets, for which the distinguishability arises due to the spatial separation of the superposed states. Here, we demonstrate superpositions composed of squeezed wavepackets, which we generate by applying an internal-state dependent force to a single trapped ion initialized in a squeezed vacuum state with 9 dB reduction in the quadrature variance. This allows us to characterise the initial sq…