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We present a native three-qubit entangling gate that exploits engineered interactions to realize control-control-target and control-target-target operations in a single coherent step. Unlike conventional decompositions into multiple…

Quantum Physics · Physics 2025-08-15 Xuexin Xu , Siyu Wang , Radhika Joshi , Rihan Hai , Mohammad H. Ansari

The difficulty of an optimization task in quantum information science depends on the proper mathematical expression of the physical target. Here we demonstrate the power of optimization functionals targeting an arbitrary perfect two-qubit…

We review quantum information processing with cold neutral particles, that is, atoms or polar molecules. First, we analyze the best suited degrees of freedom of these particles for storing quantum information, and then we discuss both…

Quantum Physics · Physics 2011-11-01 Antonio Negretti , Philipp Treutlein , Tommaso Calarco

Silicon-based quantum computing has the potential advantages of low cost, high integration density, and compatibility with CMOS technologies. The detuning mechanism has been used to experimentally achieve silicon two-qubit quantum gates and…

Mesoscale and Nanoscale Physics · Physics 2019-05-31 Tong Wu , Jing Guo

We propose a new way of implementing several elementary quantum gates for qubits in the coherent state basis. The operations are probabilistic and employ single photon subtractions as the driving force. Our schemes for single-qubit phase…

Quantum Physics · Physics 2015-05-19 Petr Marek , Jaromir Fiurasek

Key to realising quantum computers is minimising the resources required to build logic gates into useful processing circuits. While the salient features of a quantum computer have been shown in proof-of-principle experiments, difficulties…

Quantum Physics · Physics 2016-03-29 Raj B. Patel , Joseph Ho , Franck Ferreyrol , Timothy C. Ralph , Geoff J. Pryde

To be useful for quantum computation, gate operations must be maintained at high fidelities over long periods of time. In addition to decoherence, slow drifts in control hardware leads to inaccurate gates, causing the quality of operation…

Advances in development of quantum computing processors brought ample opportunities to test the performance of various quantum algorithms with practical implementations. In this paper we report on implementations of quantum compression…

Quantum Physics · Physics 2022-09-22 Matej Pivoluska , Martin Plesch

Any quantum computational network can be constructed with a sequence of the two-qubit diagonal quantum gates and one-qubit gates in two-state quantum systems. The universal construction of these quantum gates in the quantum systems and of…

Quantum Physics · Physics 2007-05-23 Xijia Miao

Given a quantum algorithm, it is highly nontrivial to devise an efficient sequence of physical gates implementing the algorithm on real hardware and incorporating topological quantum error correction. In this paper, we present a first step…

Quantum Physics · Physics 2016-08-10 Alexandru Paler , Simon J. Devitt , Austin G. Fowler

Recently there has been interest in the idea of quantum computing without control of the physical interactions between component qubits. This is highly appealing since the 'switching' of such interactions is a principal difficulty in…

Quantum Physics · Physics 2009-11-10 Simon C. Benjamin

We employ a machine learning-enabled approach to quantum state engineering based on evolutionary algorithms. In particular, we focus on superconducting platforms and consider a network of qubits -- encoded in the states of artificial atoms…

Quantum Physics · Physics 2023-01-26 Jonathon Brown , Mauro Paternostro , Alessandro Ferraro

Three-qubit quantum gates are key ingredients for quantum error correction and quantum information processing. We generate quantum-control procedures to design three types of three-qubit gates, namely Toffoli, Controlled-Not-Not and Fredkin…

Quantum Physics · Physics 2016-11-17 Ehsan Zahedinejad , Joydip Ghosh , Barry C. Sanders

In this paper, we study the optimal simulation of three-qubit unitary by using two-qubit gates. First, we give a lower bound on the two-qubit gates cost of simulating a multi-qubit gate. Secondly, we completely characterize the two-qubit…

Quantum Physics · Physics 2013-01-17 Nengkun Yu , Mingsheng Ying

We present a general technique to implement products of many qubit operators communicating via a joint harmonic oscillator degree of freedom in a quantum computer. By conditional displacements and rotations we can implement Hamiltonians…

Quantum Physics · Physics 2009-11-06 Xiaoguang Wang , Anders Sorensen , Klaus Molmer

While quantum computers promise to solve some scientifically and commercially valuable problems thought intractable for classical machines, delivering on this promise will require a large-scale quantum machine. Understanding the impact of…

An adiabatic cyclic evolution of control parameters of a quantum system ends up with a holonomic operation on the system, determined entirely by the geometry in the parameter space. The operation is given either by a simple phase factor (a…

Quantum Physics · Physics 2014-01-23 Mahn-Soo Choi

Decoherence-free subspaces allow for the preparation of coherent and entangled qubits for quantum computing. Decoherence can be dramatically reduced, yet dissipation is an integral part of the scheme in generating stable qubits and…

Quantum Physics · Physics 2009-11-07 Ben Tregenna , Almut Beige , Peter L. Knight

As quantum computing technology improves and quantum computers with a small but non-trivial number of N > 100 qubits appear feasible in the near future the question of possible applications of small quantum computers gains importance. One…

Quantum Physics · Physics 2014-08-07 Dave Wecker , Bela Bauer , Bryan K. Clark , Matthew B. Hastings , Matthias Troyer

Geometric phases have stimulated researchers for its potential applications in many areas of science. One of them is fault-tolerant quantum computation. A preliminary requisite of quantum computation is the implementation of controlled…

Quantum Physics · Physics 2015-06-26 Ranabir Das , S. K. Karthick Kumar , Anil Kumar