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Quantum computation can proceed solely through single-qubit measurements on an appropriate quantum state, such as the ground state of an interacting many-body system. We investigate a simple spin-lattice system based on the cluster-state…

Quantum Physics · Physics 2009-07-16 Andrew C. Doherty , Stephen D. Bartlett

Quantum entanglement involving coherent superpositions of macroscopically distinct states is among the most striking features of quantum theory, but its realization is challenging, since such states are extremely fragile. Using a…

Control strategies for dissipative preparation of target quantum states, both pure and mixed, and subspaces are obtained by switching between a set of available semigroup generators. We show that the class of problems of interest can be…

Quantum Physics · Physics 2015-06-17 Pierre Scaramuzza , Francesco Ticozzi

Spin-1 systems, in comparison to spin-1/2 systems, offer a better security for encoding and transfer of quantum information, primarily due to their larger Hilbert spaces. Superconducting artificial atoms possess multiple energy-levels,…

Quantum Physics · Physics 2014-12-11 Joydip Ghosh

Squeezed states of spin systems are an important entangled resource for quantum technologies, particularly quantum metrology and sensing. Here we consider the generation of spin squeezed states by interacting the spins with a dissipative…

Quantum Physics · Physics 2016-05-19 Shane Dooley , Emi Yukawa , Yuichiro Matsuzaki , George C. Knee , William J. Munro , Kae Nemoto

We propose a method for generating a spin-squeezed state that is a symmetric Dicke state, with trapped ions using only global access. The eigenstates of the ions under a strong dressing field become symmetric Dicke states and the…

Quantum Physics · Physics 2012-08-17 Atsushi Noguchi , Kenji Toyoda , Shinji Urabe

In the interaction picture, a sufficient and necessary condition that guarantees the convergence of closed quantum control system is proposed in this paper. Theoretical derivation and the proof show that it is possible to achieve the…

Mathematical Physics · Physics 2014-08-19 Shuang Cong , Yuesheng Lou , Jianxiu Liu , Sen Kuang

The transport of quantum states is a crucial aspect of information processing systems, facilitating operations such as quantum key distribution and inter-component communication within quantum computers. Most quantum networks rely on…

Quantum systems with more than two levels $-$ so-called qudits $-$ offer increased computational density and reduced circuit complexity compared to qubit-based architectures, but achieving universal and scalable control remains challenging.…

Quantum Physics · Physics 2026-05-12 Johannes K. Krondorfer , Matthias Diez , Andreas Kruckenhauser , Andreas W. Hauser

We propose an all-electrically controlled nanodevice - a gated semiconductor nanowire - capable of generating a coherent state of a single electron trapped in a harmonic oscillator or superposition of such coherent states - the…

Quantum Physics · Physics 2016-10-12 J. Pawłowski , P. Szumniak , S. Bednarek

Analog quantum simulators and digital quantum computers are two distinct paradigms driving near-term applications in modern quantum science, from probing many-body phenomena to identifying computational advantage over classical systems. A…

We demonstrate two simple theorems about squeezing induced by bilinear spin-spin interactions that conserve spin parity -- including a vast majority of quantum spin models implemented by state-of-the-art quantum simulators. In particular we…

Quantum Physics · Physics 2021-11-10 Tommaso Roscilde , Fabio Mezzacapo , Tommaso Comparin

We show that a perfect quantum state transmission can be realized through a spin chain possessing a commensurate structure of energy spectrum, which is matched with the corresponding parity. As an exposition of the mirror inversion symmetry…

Quantum Physics · Physics 2009-11-10 T. Shi , Ying Li , Z. Song , C. P. Sun

We review and compare several measures that identify quantum states that are "macroscopically quantum". These measures were initially formulated either for photonic systems or spin ensembles. Here, we compare them through a simple model…

Quantum Physics · Physics 2014-12-04 F. Fröwis , N. Sangouard , N. Gisin

The squeezed cat state, an essential quantum resource, can be used for quantum error correction and slowing decoherence of the optical cat state. However, preparing a squeezed cat state with high generation rate, and effectively…

Quantum Physics · Physics 2022-10-26 Meihong Wang , Miao Zhang , Zhongzhong Qin , Qiang Zhang , Li Zeng , Xiaolong Su , Changde Xie , Kunchi Peng

We investigate the universality of multi-spin systems in architectures of various symmetries of coupling type and topology. Explicit reachability sets under symmetry constraints are provided. Thus for a given (possibly symmetric)…

Quantum Physics · Physics 2009-05-17 U. Sander , T. Schulte-Herbrueggen

Quantum superpositions of macroscopically distinct classical states, so-called Schr\"{o}dinger cat states, are a resource for quantum metrology, quantum communication, and quantum computation. In particular, the superpositions of two…

In classical control theory, tracking refers to the ability to perform measurements and feedback on a classical system in order to enforce some desired dynamics. In this paper we investigate a simple version of quantum tracking, namely, we…

Quantum Physics · Physics 2008-11-20 Paulo E. M. F. Mendonca , Alexei Gilchrist , Andrew C. Doherty

Simulating physical systems on near-term quantum computers often requires preparing states within constrained subspaces, like those with fixed particle number or spin. We use Lie algebraic techniques to prove that hardware-efficient gates…

Quantum Physics · Physics 2026-05-05 Andreas Stergiou , Nicolas PD Sawaya

We provide a set of rules to define several spinful quantum Hall model states. The method extends the one known for spin polarized states. It is achieved by specifying an undressed root partition, a squeezing procedure and rules to dress…

Strongly Correlated Electrons · Physics 2011-11-23 E. Ardonne , N. Regnault