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The Hilbert space in PT-symmetric quantum mechanics is formulated as a linear vector space with a dynamic inner product. The most general PT-symmetric matrix Hamiltonians are constructed for 2*2 and 3*3 cases. In the former case, the…

Quantum Physics · Physics 2015-05-18 Qing-hai Wang , Song-zhi Chia , Jie-hong Zhang

Feedback control is an essential component of many modern technologies and provides a key capability for emergent quantum technologies. We extend existing approaches of direct feedback control in which the controller applies a function…

Quantum Physics · Physics 2020-12-15 Hui Chen , Hanhan Li , Felix Motzoi , Leigh S. Martin , K. Birgitta Whaley , Mohan Sarovar

We consider algebras underlying Hilbert spaces used by quantum information algorithms. We show how one can arrive at equations on such algebras which define n-dimensional Hilbert space subspaces which in turn can simulate quantum systems on…

Quantum Physics · Physics 2007-05-23 Mladen Pavicic

We present a novel, computationally efficient approach to accelerate quantum optimal control calculations of large multi-qubit systems used in a variety of quantum computing applications. By leveraging the intrinsic symmetry of finite…

Quantum Physics · Physics 2023-10-05 Xian Wang , Mahmut Sait Okyay , Anshuman Kumar , Bryan M. Wong

We describe the implications of permutation symmetry for the state space and dynamics of quantum mechanical systems of matrices of general size $N$. We solve the general 11- parameter permutation invariant quantum matrix harmonic oscillator…

High Energy Physics - Theory · Physics 2022-12-14 George Barnes , Adrian Padellaro , Sanjaye Ramgoolam

Quasi-integrable Hamiltonian systems are of great interest in many research fields of physics and mathematics. In these systems, the phase space has regular and chaotic trajectories. These trajectories depend in part on the magnitude of…

Plasma Physics · Physics 2014-04-14 Vilarbo da Silva , Alexsandro M. Carvalho

A controlled quantum system possesses a search landscape defined by the target physical objective as a function of the controls. This paper focuses on the landscape for the transition probability Pif between the states of a finite level…

Chemical Physics · Physics 2015-05-27 Vincent Beltrani , Jason Dominy , Tak-San Ho , Herschel Rabitz

We characterise a model of universal quantum computation where the register (computational) qubits are controlled by ancillary qubits, using only a single fixed interaction between register and ancillary qubits. No additional access is…

Quantum Physics · Physics 2013-10-25 Timothy J. Proctor , Erika Andersson , Viv Kendon

A finite dimensional system with a quadratic Hamiltonian constraint is Dirac quantized in holomorphic, antiholomorphic and mixed representations. A unique inner product is found by imposing Hermitian conjugacy relations on an operator…

General Relativity and Quantum Cosmology · Physics 2010-11-01 Jorma Louko

The Cartan control problem of the quantum circuits discussed from the differential geometry point of view. Abstract unitary transformations of $SU(2^n)$ are realized physically in the projective Hilbert state space $CP(2^n-1)$ of the…

General Physics · Physics 2008-10-20 Peter Leifer

We present a data-driven optimal control framework that can be viewed as a generalization of the path integral (PI) control approach. We find iterative feedback control laws without parameterization based on probabilistic representation of…

Systems and Control · Computer Science 2016-02-02 Yunpeng Pan , Evangelos A. Theodorou , Michail Kontitsis

Over an arbitrary commutative ring $R$, we develop a theory of quantum cellular automata. We then use algebraic K-theory to construct a space $\mathbf{Q}(X)$ of quantum cellular automata (QCA) on a given metric space $X$. In most cases of…

Algebraic Topology · Mathematics 2026-03-04 Mattie Ji , Bowen Yang

Geometric quantum computation offers a practical strategy toward robust quantum computation due to its inherently error tolerance. However, the rigorous geometric conditions lead to complex and/or error-disturbed quantum controls,…

Quantum Physics · Physics 2022-07-28 Tao Chen , Zheng-Yuan Xue , Z. D. Wang

We survey some of the main conceptual developments in the study of PT-symmetric and pseudo-Hermitian Hamiltonian operators that have taken place during the past ten years or so. We offer a precise mathematical description of a quantum…

Quantum Physics · Physics 2015-05-19 Ali Mostafazadeh

Optimal decentralized controller design is notoriously difficult, but recent research has identified large subclasses of such problems that may be convexified and thus are amenable to solution via efficient numerical methods. One recently…

Systems and Control · Computer Science 2014-11-25 Laurent Lessard , Sanjay Lall

In computer simulations, quantum delocalization of atomic nuclei can be modeled making use of the Path Integral (PI) formulation of quantum statistical mechanics. This approach, however, comes with a large computational cost. By restricting…

Statistical Mechanics · Physics 2015-04-13 Karsten Kreis , Mark E. Tuckerman , Davide Donadio , Kurt Kremer , Raffaello Potestio

A diagonalizable non-Hermitian Hamiltonian having a real spectrum may be used to define a unitary quantum system, if one modifies the inner product of the Hilbert space properly. We give a comprehensive and essentially self-contained review…

Quantum Physics · Physics 2015-05-13 Ali Mostafazadeh

We present for the first time a general theory of error correction for permutation invariant (PI) codes. Using representation theory of the symmetric group we construct efficient algorithms that can correct any correctible error on any PI…

Quantum Physics · Physics 2026-02-17 Yingkai Ouyang , Gavin K. Brennen

Position-deformed Heisenberg algebra with maximal length uncertainty has recently been proven to induce strong quantum gravitational fields at the Planck scale (2022 J. Phys. A: Math. Theor.55 105303). In the present study, we use the…

High Energy Physics - Theory · Physics 2022-05-02 Latévi M. Lawson , Prince K. Osei , Komi Sodoga , Fred Soglohu

A closed quantum system is defined as completely controllable if an arbitrary unitary transformation can be executed using the available controls. In practice, control fields are a source of unavoidable noise. Can one design control fields…

Quantum Physics · Physics 2015-05-27 Michael Khasin , Ronnie Kosloff