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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

We demonstrate high fidelity entangling quantum gates within a chain of five trapped ion qubits by optimally shaping optical fields that couple to multiple collective modes of motion. We individually address qubits with segmented optical…

Quantum Physics · Physics 2014-05-20 T. Choi , S. Debnath , T. A. Manning , C. Figgatt , Z. -X. Gong , L. -M. Duan , C. Monroe

Preparation of a target quantum many-body state on quantum simulators is one of the significant steps in quantum science and technology. With a small number of qubits, a few quantum states, such as the Greenberger-Horne-Zeilinger state,…

Quantum Physics · Physics 2023-07-28 Donggyu Kim , Eun-Gook Moon

We demonstrate and contrast two approaches to the stabilization of qubit entanglement by feedback. Our demonstration is built on a feedback platform consisting of two superconducting qubits coupled to a cavity which are measured by a…

Lindbladian dynamics of open systems may be employed to steer a many-body system towards a non-trivial ground state of a local Hamiltonian. Such protocols provide us with tunable platforms facilitating the engineering and study of…

Quantum Physics · Physics 2025-06-24 Yi-Xuan Wang , Yuval Gefen

In this paper we discuss a quantum multi-tasking protocol for preparation of known one-qubit and two-qubit states respectively in two different locations. The ideal remote state preparation protocol is discussed in the first place in which…

Quantum Physics · Physics 2023-01-27 Binayak S. Choudhury , Manoj Kumar Mandal , Soumen Samanta , Biswanath Dolai

Applying post selection in each step of an iterated protocol leads to sensitive quantum dynamics that may be utilized to test and benchmark current quantum computers. An example of this type of protocols was originally proposed for the task…

Quantum Physics · Physics 2024-10-10 Adrian Ortega , Orsolya Kálmán , Tamás Kiss

We propose and analyse a scheme for single-rail-encoded arbitrary multi-qubit quantum-state generation to provide a versatile tool for quantum optics and quantum information applications. Our scheme can be realized, for small numbers of…

Quantum Physics · Physics 2016-10-18 Farid Shahandeh , Austin P. Lund , Timothy C. Ralph , Michael R. Vanner

We propose an efficient protocol to estimate the fidelity of an $n$-qubit entangled measurement device, requiring only qubit state preparations and classical data post-processing. It works by measuring the eigenstates of Pauli operators,…

Quantum Physics · Physics 2023-12-22 Zanqiu Shen , Kun Wang

We demonstrate one-sided device-independent self-testing of any pure entangled two-qubit state based on a fine-grained steering inequality. The maximum violation of a fine-grained steering inequality can be used to witness certain steerable…

Quantum Physics · Physics 2020-05-06 Zhihao Bian , A. S. Majumdar , C. Jebaratnam , Kunkun Wang , Lei Xiao , Xiang Zhan , Yongsheng Zhang , Peng Xue

We discuss experimental effects in the implementation of a recent scheme for performing bus mediated entangling operations between qubits. Here a bus mode, a strong coherent state, successively undergoes weak Kerr-type non-linear…

Quantum Physics · Physics 2008-05-19 Peter P. Rohde , William J. Munro , Timothy C. Ralph , Peter van Loock , Kae Nemoto

In order to achieve fault-tolerant quantum computation, we need to repeat the following sequence of four steps: First, perform 1 or 2 qubit quantum gates (in parallel if possible). Second, do a syndrome measurement on a subset of the…

Quantum Physics · Physics 2024-12-11 Harry Buhrman , Marten Folkertsma , Bruno Loff , Niels M. P. Neumann

Recently, a different form of quantum steering, i.e., certification of quantum steering in a one-sided semi-device-independent way, has been formulated [Jebarathinam \etal Phys. Rev. A 108, 042211 (2023)]. In this work, we use this…

Quantum Physics · Physics 2025-07-22 Chellasamy Jebarathinam , Debarshi Das , Huan-Yu Ku , Debasis Sarkar , Hsi-Sheng Goan

We consider a mechanism to generate controllable qudit-qudit interactions in a charge-position paradigm for a quantum computer, through the use of auxiliary states. By controlling the tunneling rates onto these auxiliaries from the qudits…

Quantum Physics · Physics 2007-05-23 S. G. Schirmer , A. D. Greentree , D. K. L. Oi

State transfer across discrete quantum networks is one of the elementary tasks of quantum information processing. Its aim is the faithful placement of information into a specific position in the network. However, all physical systems suffer…

Quantum Physics · Physics 2014-12-30 Holger Frydrych , Antonín Hoskovec , Gernot Alber , Igor Jex

Cluster states are a useful resource in quantum computation, and can be generated by applying entangling gates between next-neighbor qubits. Heralded entangling gates offer the advantage of high post-selected fidelity, and can be used to…

Quantum Physics · Physics 2025-07-29 Luke M. Stewart , Gefen Baranes , Joshua Ramette , Josiah Sinclair , Vladan Vuletić

Einstein-Podolsky-Rosen (EPR) steering is the ability that an observer persuades a distant observer to share entanglement by making local measurements. Determining a quantum state is steerable or unsteerable remains an open problem. Here,…

Quantum Physics · Physics 2021-03-09 Xiao-Gang Fan , Huan Yang , Fei Ming , Xue-Ke Song , Dong Wang , Liu Ye

Verifying the proper preparation of quantum states is essential in modern quantum information science. Various protocols have been developed to estimate the fidelity of quantum states produced by different parties. Direct fidelity…

Quantum Physics · Physics 2024-12-11 Christopher Vairogs , Bin Yan

Engineered dissipation provides a powerful route to controlling and stabilizing quantum states in open systems. Superconducting circuits are particularly suited to this approach due to their tunable coupling to dissipative environments.…

Quantum Physics · Physics 2026-05-13 Qihao Guo , Botao Du , Ruichao Ma

Recent work has shown that use of quantum feedback can significantly enhance both the speed and success rate of measurement-based remote entanglement generation, but it is generally unknown what feedback protocols are optimal for these…

Quantum Physics · Physics 2017-07-17 Leigh S. Martin , Mahrud Sayrafi , K. Birgitta Whaley