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The local conservation of a physical quantity whose distribution changes with time is mathematically described by the continuity equation. The corresponding time parameter, however, is defined with respect to an idealized classical clock.…

Chemical Physics · Physics 2018-11-21 Axel Schild

The simulation of quantum dynamics calls for quantum algorithms working in first quantized grid encodings. Here, we propose a variational quantum algorithm for performing quantum dynamics in first quantization. In addition to the usual…

Parameterized quantum circuits are a promising technology for achieving a quantum advantage. An important application is the variational simulation of time evolution of quantum systems. To make the most of quantum hardware, variational…

Quantum Physics · Physics 2021-07-28 Marcello Benedetti , Mattia Fiorentini , Michael Lubasch

There is a solution to the problem of asymptotic completeness in many body scattering theory that offers a specific view of the quantum unitary dynamics which allows for the straightforward introduction of local time for every, at least…

Quantum Physics · Physics 2014-09-18 J. Jeknic-Dugic , M. Arsenijevic , M. Dugic

The classical and quantum dynamics of simple time-reparametrization- invariant models containing two degrees of freedom are studied in detail. Elimination of one ``clock'' variable through the Hamiltonian constraint leads to a description…

General Relativity and Quantum Cosmology · Physics 2009-10-28 Ian D. Lawrie , Richard J. Epp

We study classical Hamiltonian systems in which the intrinsic proper time evolution parameter is related through a probability distribution to the physical time, which is assumed to be discrete. In this way, a physical clock with discrete…

Quantum Physics · Physics 2007-05-23 H. -T. Elze

We propose a new point of view regarding the problem of time in quantum mechanics, based on the idea of replacing the usual time operator $\mathbf{T}$ with a suitable real-valued function $T$ on the space of physical states. The proper…

In the past few decades, researchers have created a veritable zoo of quantum algorithms by drawing inspiration from classical computing, information theory, and even from physical phenomena. Here we present quantum algorithms for…

Quantum Physics · Physics 2025-10-02 N. L. Diaz , Paolo Braccia , Martin Larocca , J. M. Matera , R. Rossignoli , M. Cerezo

It is expected that a quantum theory of gravity will radically alter our current notion of spacetime geometry. However, contrary to what was commonly assumed for many decades, quantum gravity effects could manifest in scales much larger…

General Relativity and Quantum Cosmology · Physics 2026-05-14 Eduardo A. B. Oliveira , Andre G. S. Landulfo

An extension of standard quantum mechanics is proposed in which the Newtonian time appearing as a parameter in the unitary evolution operator is replaced with the time shown by a `quantum clock'. Such a clock is defined by the following…

Quantum Physics · Physics 2026-03-17 Dorje C. Brody , Lane P. Hughston

We introduce a novel hybrid algorithm to simulate the real-time evolution of quantum systems using parameterized quantum circuits. The method, named "projected - Variational Quantum Dynamics" (p-VQD) realizes an iterative, global projection…

Quantum Physics · Physics 2021-07-28 Stefano Barison , Filippo Vicentini , Giuseppe Carleo

We introduce an original model of quantum phenomena, a model that provides a picture of a "deep structure", an "underlying pattern" of quantum dynamics. We propose that the source of a particle and all of that particle's possible detectors…

Quantum Physics · Physics 2007-05-23 Pavel Kurakin , George Malinetskii , Howard Bloom

Currently, 'time' does not play any essential role in quantum information theory. In this sense, quantum information theory is underdeveloped similarly to how quantum physics was underdeveloped before Erwin Schrodinger introduced his famous…

Mesoscale and Nanoscale Physics · Physics 2019-09-04 Mohammad H. Ansari , Alwin van Steensel , Yuli V. Nazarov

We propose a new variational quantum algorithm, which we refer to as TIMES-ADAPT, that prepares time-evolved states in a low-energy or symmetric subspace of a time-independent Hamiltonian on a quantum computer. Using a specially trained…

We show that a one-dimensional chain of trapped ions can be engineered to produce a quantum mechanical system with discrete scale invariance and fractal-like time dependence. By discrete scale invariance we mean a system that replicates…

Quantum Gases · Physics 2019-07-31 Dean Lee , Jacob Watkins , Dillon Frame , Gabriel Given , Rongzheng He , Ning Li , Bing-Nan Lu , Avik Sarkar

Quantum algorithms for quantum dynamics simulations are traditionally based on implementing a Trotter-approximation of the time-evolution operator. This approach typically relies on deep circuits and is therefore hampered by the substantial…

Quantum Physics · Physics 2022-01-06 Alexander Miessen , Pauline J. Ollitrault , Ivano Tavernelli

Time symmetry in quantum mechanics, where the current quantum state is determined jointly by both the past and the future, offers a more comprehensive description of physical phenomena. This symmetry facilitates both forward and backward…

Quantum Physics · Physics 2025-06-13 Shijie Wei , Jingwei Wen , Xiaogang Li , Peijie Chang , Bozhi Wang , Franco Nori , Guilu Long

Feynman's model of a quantum computer provides an example of a continuous-time quantum walk. Its clocking mechanism is an excitation of a basically linear chain of spins with occasional controlled jumps which allow for motion on a planar…

Quantum Physics · Physics 2009-11-11 Diego de Falco , Dario Tamascelli

We propose a general-purpose, self-adaptive approach to construct variational wavefunction ans\"atze for highly accurate quantum dynamics simulations based on McLachlan's variational principle. The key idea is to dynamically expand the…

One approach to defining dynamics for quantum gravity in a naturally timeless setting is to select a suitable matter degree of freedom as a 'clock' before quantisation. This idea of deparametrisation was recently introduced in group field…

General Relativity and Quantum Cosmology · Physics 2021-04-15 Steffen Gielen , Axel Polaczek