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We show that we can achieve global density-operator controllability for most N-dimensional bilinear Hamiltonian control systems with general fixed couplings using a single, locally-acting actuator that modulates one energy-level transition.…

Quantum Physics · Physics 2009-11-13 Sonia G. Schirmer , Ivan C. H. Pullen , Peter J. Pemberton-Ross

We demonstrate that in a coupled two-qubit system any single-qubit gate can be decomposed into two conditional two-qubit gates and that any conditional two-qubit gate can be implemented by a manipulation analogous to that used for a…

Quantum Physics · Physics 2009-11-11 Zhongyuan Zhou , Shih-I Chu , Siyuan Han

We prove the existence of a unitary transformation that enables two arbitrarily given Hamiltonians in the same Hilbert space to be transformed into one another. The result is straightforward yet, for example, it lays the foundation to…

Quantum Physics · Physics 2020-12-09 Lian-Ao Wu , Dvira Segal

We quantify the capability of creating entanglement for a general physical interaction acting on two qubits. We give a procedure for optimizing the generation of entanglement. We also show that a Hamiltonian can create more entanglement if…

Quantum Physics · Physics 2011-06-02 W. Dür , G. Vidal , J. I. Cirac , N. Linden , S. Popescu

While quantum simulation is one of the most promising applications of modern quantum devices, accessible simulation times are fundamentally limited by finite coherence times due to omnipresent noise. Based on the ideas of relational…

Quantum Physics · Physics 2025-09-03 Sebastian Gemsheim , Felix Fritzsch

An efficient and intuitive framework for universal quantum computation is presented that uses pairs of spin-1/2 particles to form logical qubits and a single physical interaction, Heisenberg exchange, to produce all gate operations. Only…

Quantum Physics · Physics 2016-09-08 Jeremy Levy

Quantum simulation is a promising near term application for mesoscale quantum information processors, with the potential to solve computationally intractable problems at the scale of just a few dozen interacting quantum systems. Recent…

Quantum Physics · Physics 2014-08-14 David L. Hayes , Steven T. Flammia , Michael J. Biercuk

The quantum approximate optimization algorithm (QAOA) applies two Hamiltonians to a quantum system in alternation. The original goal of the algorithm was to drive the system close to the ground state of one of the Hamiltonians. This paper…

Quantum Physics · Physics 2018-12-31 Seth Lloyd

We examine the problem of determining if a 2-local Hamiltonian is stoquastic by local basis changes. We analyze this problem for two-qubit Hamiltonians, presenting some basic tools and giving a concrete example where using unitaries beyond…

Quantum Physics · Physics 2019-05-08 Joel Klassen , Barbara M. Terhal

All-to-all interactions arise naturally in many areas of theoretical physics and across diverse experimental quantum platforms, motivating a systematic study of their information-processing power. Assuming each pair of qubits interacts with…

Quantum Physics · Physics 2025-10-01 Chao Yin

Hamiltonian quantum gates controlled by classical electromagnetic fields form the basis of any realistic model of quantum computers. In this letter, we derive a lower bound on the field energy required to implement such gates and relate…

Quantum Physics · Physics 2025-10-15 Josey Stevens , Sebastian Deffner

A non-local unitary transformation of two qubits occurs when some Hamiltonian interaction couples them. Here we characterize the amount, as measured by time, of interaction required to perform two--qubit gates, when also arbitrarily fast,…

Quantum Physics · Physics 2009-11-07 K. Hammerer , G. Vidal , J. I. Cirac

Digital-analog quantum computing is a computational paradigm which employs an analog Hamiltonian resource together with single-qubit gates to reach universality. Here, we design a new scheme which employs an arbitrary two-body source…

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

From the time dependence of states of one of them, the dynamics of two interacting qubits is determined to be one of two possibilities that differ only by a change of signs of parameters in the Hamiltonian. The only exception is a simple…

Quantum Physics · Physics 2009-11-13 Thomas F. Jordan , Anil Shaji , E. C. G. Sudarshan

Implementing quantum operations in the form of natural Hamiltonian dynamics is desirable, since they almost require no external control or feedback. In this work, we propose a NISQ-friendly quantum-classical hybrid approach to designing a…

Quantum Physics · Physics 2024-09-23 Arunava Majumder , Dylan Lewis , Akshaya Jayashankar , V. S. Prasannaa , Sougato Bose

Motivated by experimental limitations commonly met in the design of solid state quantum computers, we study the problems of non-local Hamiltonian simulation and non-local gate synthesis when only homogeneous local unitaries are performed in…

Quantum Physics · Physics 2007-05-23 Ll. Masanes , G. Vidal , J. I. Latorre

The Heisenberg exchange interaction is a natural method to implement non-local (i.e., multi-qubit) quantum gates in quantum information processing. We consider quantum circuits comprising of $(SWAP)^\alpha $ gates, which are realized…

Quantum Physics · Physics 2009-11-10 Heng Fan , Vwani Roychowdhury , Thomas Szkopek

The circuit-to-Hamiltonian construction translates dynamics (a quantum circuit and its output) into statics (the groundstate of a circuit Hamiltonian) by explicitly defining a quantum register for a clock. The standard Feynman-Kitaev…

Quantum Physics · Physics 2014-05-20 Nikolas P. Breuckmann , Barbara M. Terhal

Manipulating Hamiltonians governing physical systems has found a broad range of applications, from quantum chemistry to semiconductor design. In this work, we provide a new way of manipulating Hamiltonians, by transforming their eigenvalues…

Quantum Physics · Physics 2025-04-30 Tatsuki Odake , Hlér Kristjánsson , Philip Taranto , Mio Murao