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The relation between the thermodynamic entropy production and non-Markovian evolutions is matter of current research. Here, we study the behavior of the stochastic entropy production in open quantum systems undergoing unital non-Markovian…

Quantum Physics · Physics 2020-08-19 Stefano Gherardini , Stefano Marcantoni , Filippo Caruso

Reliably transmitting quantum information via a noisy quantum channel is a central challenge in quantum information science. While constructing a decoder is crucial to this goal, little was known about quantum circuit implementations of…

Quantum Physics · Physics 2026-03-18 Takeru Utsumi , Yoshifumi Nakata

An investigation of an optimal universal unitary Controlled-NOT gate that performs a specific operation on two unknown states of qubits taken from a great circle of the Bloch sphere is presented. The deep analogy between the optimal…

Quantum Physics · Physics 2010-11-02 Michael Siomau , Stephan Fritzsche

A qubit chosen from equatorial or polar great circles on a Bloch sphere can be remotely prepared with an Einstain-Podolsky-Rosen (EPR) state shared and a cbit communication. We generalize this protocal into an arbitrary longitudinal qubit…

Quantum Physics · Physics 2007-05-23 Xinhua Peng , Xiwen Zhu , Maili Liu , Kelin Gao

We study the operational regime of a noiseless linear amplifier based on quantum scissors that can nondeterministically amplify the one photon component of a quantum state with weak excitation. It has been shown that an arbitrarily large…

Quantum Physics · Physics 2014-11-04 J. Bernu , S. Armstrong , T. Symul , T. C. Ralph , P. K. Lam

We propose a protocol for realizing a Toffoli gate using neutral-atom qubits in optical tweezers. Two ground-state hyperfine levels of the atoms are considered as qubit states. Our method relies on the strong and long-range interactions…

Quantum Physics · Physics 2025-07-04 Sinchan Snigdha Rej , Bimalendu Deb

We study reliable quantum information processing (QIP) under two different types of environment. First type is Markovian exponential decay, and the appropriate elementary strategy of protection of qubit is to apply fast gates. The second…

Quantum algorithms manipulate the amplitudes of quantum states to find solutions to computational problems. In this work, we present a framework for applying a general class of non-linear functions to the amplitudes of quantum states, with…

Quantum Physics · Physics 2023-09-19 Arthur G. Rattew , Patrick Rebentrost

We propose a quantum circuit composed of $cNOT$ gates and four single-qubit gates to generate a $W$ state of three qubits. This circuit was then enhanced by integrating two-qubit gates to create a $W$ state of four and five qubits. After a…

Quantum Physics · Physics 2025-08-28 Firat Diker

We employ a quantum Langevin equation approach to establish non-Markovian dynamical equations, on a fully microscopic basis, to investigate the measurement of the state of a coupled quantum dot qubit by a nearby quantum point contact. The…

Mesoscale and Nanoscale Physics · Physics 2009-11-11 Bing Dong , Norman J. M. Horing , X. L. Lei

We present three different matrix bases that can be used to decompose density matrices of d--dimensional quantum systems, so-called qudits: the generalized Gell-Mann matrix basis, the polarization operator basis, and the Weyl operator…

Quantum Physics · Physics 2007-06-13 Reinhold A. Bertlmann , Philipp Krammer

Quantum circuit depth minimization is critical for practical applications of circuit-based quantum computation. In this work, we present a systematic procedure to decompose multiqubit controlled unitary gates, which is essential in many…

Quantum Physics · Physics 2022-10-06 Adenilton J. da Silva , Daniel K. Park

The Bloch vector's path of a two-level system exposed to a monochromatic field exhibits, in the regime of strong coupling, complex corkscrew trajectories. By considering the infinitesimal evolution of the two-level system when the field is…

Quantum Physics · Physics 2013-09-09 Giuliano Benenti , Stefano Siccardi , Giuliano Strini

As physical systems, qubits must evolve from input to output state. We describe a simple scheme in which the effect of a quantum gate is described by the action of an effective Hamiltonian acting for some characteristic time. This model…

Quantum Physics · Physics 2026-04-21 M. P. Vaughan

Quantum state preparation is a crucial process within numerous quantum algorithms, and the need for efficient initialization of quantum registers is ever increasing as demand for useful quantum computing grows. The problem arises as the…

Quantum Physics · Physics 2024-09-11 Andrew Wright , Marco Lewis , Paolo Zuliani , Sadegh Soudjani

Non-Markovian noise, arising from the memory effect in the environment, poses substantial challenges to conventional quantum noise suppression protocols, including quantum error correction and mitigation. We introduce a channel…

Quantum Physics · Physics 2024-12-17 Zhenhuan Liu , Yunlong Xiao , Zhenyu Cai

In this paper, we present an algorithm for preparing quantum states of the form $\sum_{i=0}^{n-1} \alpha_i |i\rangle$, where the coefficients $\alpha_i$ are specified by a quantum oracle. Our method achieves this task twice as fast as the…

Quantum Physics · Physics 2025-06-17 Artem Chernikov , Karina Zakharova , Sergey Sysoev

Quantum optical amplification that beats the noise addition limit for deterministic amplifiers has been realized experimentally using several different nondeterministic protocols. These schemes either require single-photon sources, or…

Quantum manipulation protocols for quantum sensors and quantum computation often require many single qubit rotations. However, the impact of phase noise in the field that performs the qubit rotations is often neglected or treated only for…

Quantum Physics · Physics 2012-10-11 Zilong Chen , Justin G. Bohnet , Joshua M. Weiner , James K. Thompson

Reinforcement learning has witnessed recent applications to a variety of tasks in quantum programming. The underlying assumption is that those tasks could be modeled as Markov Decision Processes (MDPs). Here, we investigate the feasibility…

Quantum Physics · Physics 2024-06-06 M. Sohaib Alam , Noah F. Berthusen , Peter P. Orth
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