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We present a simple proof of the minimum time for the quantum evolution between two arbitrary states. This proof is performed in the absence of any geometrical arguments. Then, being in the geometric framework of quantum evolutions based…

Quantum Physics · Physics 2021-08-17 Carlo Cafaro , Paul M. Alsing

We show that the total time of evolution from the initial quantum state to final quantum state and then back to the initial state, i.e., making a round trip along the great circle over S^2, must have a lower bound in quantum mechanics, if…

Quantum Physics · Physics 2008-11-26 Pulak Ranjan Giri

We derive a Geometric quantum speed limit (QSL) for imaginary-time evolution, where the dynamics is governed by a non-unitary Schr\"{o}dinger equation. By introducing a cost function based on the angular distance between the normalized…

Quantum Physics · Physics 2025-08-15 Kohei Kobayashi

In this work we derive a lower bound for the minimum time required to implement a target unitary transformation through a classical time-dependent field in a closed quantum system. The bound depends on the target gate, the strength of the…

Quantum Physics · Physics 2017-11-22 Christian Arenz , Benjamin Russell , Daniel Burgarth , Herschel Rabitz

For both unitary and open qubit dynamics, we compare asymmetry monotone-based bounds on the minimal time required for an initial qubit state to evolve to a final qubit state from which it is probabilistically distinguishable with fixed…

Quantum Physics · Physics 2018-10-02 T. J. Volkoff , K. B. Whaley

The evaluation of the minimal evolution time between two distinguishable states of a system is important for assessing the maximal speed of quantum computers and communication channels. Lower bounds for this minimal time have been proposed…

Quantum Physics · Physics 2013-02-01 M. M. Taddei , B. M. Escher , L. Davidovich , R. L. de Matos Filho

The laws of quantum physics place a limit on the speed of computation. In particular, the evolution time of a system from an initial state to a final state cannot be arbitrarily short. Bounds on the speed of evolution for unitary dynamics…

Quantum Physics · Physics 2025-07-09 Zihao Hu , Haidong Yuan , Zigui Zhang , Chi-Hang Fred Fung , Zibo Miao

We introduce a two-dimensional discrete-time dynamical system which represents the evolution of an angle and angular velocity. While the angle evolves by a fixed amount in every step, the evolution of the angular velocity is governed by a…

Dynamical Systems · Mathematics 2024-12-20 Aakash Khandelwal , Ranjan Mukherjee

Finding minimal time and establishing the structure of the corresponding optimal controls which can transfer a given initial state of a quantum system into a given target state is a key problem of quantum control. In this work, this problem…

Quantum Physics · Physics 2025-02-21 L. V. Lokutsievskiy , A. N. Pechen , M. I. Zelikin

The existence of a minimum measurable length scale was suggested by various theories of quantum gravity, string theory and black hole physics. Motivated by this, we examine a quantum theory exhibiting a minimum measurable time scale. We use…

Quantum Physics · Physics 2024-11-22 Ziemowit Domański

We formulate Grover's unstructured search algorithm as a chiral quantum walk, where transitioning in one direction has a phase conjugate to transitioning in the opposite direction. For small phases, this breaking of time-reversal symmetry…

Quantum Physics · Physics 2015-09-22 Thomas G. Wong

Variational quantum time evolution allows us to simulate the time dynamics of quantum systems with near-term compatible quantum circuits. Due to the variational nature of this method the accuracy of the simulation is a priori unknown. We…

Quantum Physics · Physics 2023-10-25 Christa Zoufal , David Sutter , Stefan Woerner

We extend the work in New J. Phys. 19, 103015 (2017) by deriving a lower bound for the minimum time necessary to implement a unitary transformation on a generic, closed quantum system with an arbitrary number of classical control fields.…

Quantum Physics · Physics 2018-07-04 Juneseo Lee , Christian Arenz , Herschel Rabitz , Benjamin Russell

We introduce an iterative method to search for time-optimal Hamiltonians that drive a quantum system between two arbitrary, and in general mixed, quantum states. The method is based on the idea of progressively improving the efficiency of…

Quantum Physics · Physics 2019-12-25 Francesco Campaioli , William Sloan , Kavan Modi , Felix Alexander Pollock

We propose a novel method to sequentially optimize arbitrary single-qubit gates in parameterized quantum circuits for simulating real and imaginary time evolution. The method utilizes full degrees of freedom of single-qubit gates and…

We show that optimizing a quantum gate for an open quantum system requires the time evolution of only three states irrespective of the dimension of Hilbert space. This represents a significant reduction in computational resources compared…

Quantum Physics · Physics 2021-02-16 Michael H. Goerz , Daniel M. Reich , Christiane P. Koch

We consider the problem of controlling in minimum time a two-level quantum system which can be subject to a drift. The control is assumed to be bounded in magnitude, and to affect two or three independent generators of the dynamics. We…

Quantum Physics · Physics 2015-10-28 Raffaele Romano

We study the minimum time related to the quantum speed limit that characterizes the evolution of an open quantum system with the help of a simple model in the short and long time limits. We compare in particular the situation corresponding…

Quantum Physics · Physics 2016-04-12 Jean Richert , Tarek Khalil

We study the optimal quantum control of heteronuclear two-qubit systems described by a Hamiltonian containing both nonlocal internal drift and local control terms. We derive an explicit formula to compute the minimum time required to steer…

Quantum Physics · Physics 2013-11-07 Bin Li , Zu-Huan Yu , Shao-Ming Fei , XianQing Li-Jost

Following a recent proposal of L. Wang and D. Babikov, J. Chem. Phys. 137, 064301 (2012), we theoretically illustrate the possibility of using the motional states of a $Cd^+$ ion trapped in a slightly anharmonic potential to simulate the…

Quantum Physics · Physics 2015-04-14 Ludovic Santos , Yves Justum , Nathalie Vaeck , M. Desouter-Lecomte
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