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Wootters [PRL 80, 2245 (1998)] has derived a closed formula for the entanglement of formation (EOF) of an arbitrary mixed state in a system of two qubits. There is no known closed form expression for the EOF of an arbitrary mixed state in…

Quantum Physics · Physics 2009-11-10 Edward Gerjuoy

We study the entanglement of tripartite quantum states and provide analytical lower bound of concurrence in terms of the concurrence of sub-states. The lower bound may improve all the existing lower bounds of concurrence. The approach is…

Quantum Physics · Physics 2012-08-09 Xue-Na Zhu , Ming-Jing Zhao , Shao-Ming Fei

A lower bound on the amount of noise that must be added to a GHZ-like entangled state to make it separable (also called the random robustness) is found using the transposition condition. The bound is applicable to arbitrary numbers of…

Quantum Physics · Physics 2009-11-06 P. Deuar , W. J. Munro , K. Nemoto

Preparing quantum thermal states on a quantum computer is in general a difficult task. We provide a procedure to prepare a thermal state on a quantum computer with a logarithmic depth circuit of local quantum channels assuming that the…

Quantum Physics · Physics 2019-02-13 Fernando G. S. L. Brandao , Michael J. Kastoryano

In the presence of chemical potential and temperature, we holographically study subregion complexity in a non-conformal quantum field theory with a critical point. We propose a new interpretation according to which the states, needing…

High Energy Physics - Theory · Physics 2023-06-14 Mohammad Ali-Akbari , Mahsa Lezgi

We present a lower bound of concurrence for arbitrary dimensional bipartite quantum states. This lower bound may be used to improve all the known lower bounds of concurrence. Moreover, the lower bound gives rise to an operational sufficient…

Quantum Physics · Physics 2011-12-26 Ming-Jing Zhao , Xue-Na Zhu , Shao-Ming Fei , Xianqing Li-Jost

The conventional approach to understanding the characteristics of an unknown quantum state involves having numerous identical independent copies of the system in that state. However, we demonstrate that gleaning insights into specific…

Quantum Physics · Physics 2024-04-09 Nengkun Yu

Calculating the physical properties of quantum thermal states is a difficult problem for classical computers, rendering it intractable for most quantum many-body systems. A quantum computer, by contrast, would make many of these…

Strongly Correlated Electrons · Physics 2019-11-19 John Martyn , Brian Swingle

The optimization of quantum circuit depth is crucial for practical quantum computing, as limited coherence times and error-prone operations constrain executable algorithms. Measurement and feedback operations are fundamental in quantum…

Quantum Physics · Physics 2025-03-21 Wei Zi , Junhong Nie , Xiaoming Sun

Measuring the closest distance between two states is an alternative and significant approach in the resource quantification, which is the core task in the resource theory. Quite limited progress has been made for this approach even in…

Quantum Physics · Physics 2022-03-16 Li-qiang Zhang , Deng-hui Yu , Chang-shui Yu

Calculation of the quantum discord requires to find the minimum of the quantum conditional entropy $S(\rho^{AB}|\{\Pi^B_{k}\})$ over all measurements on the subsystem $B$. In this paper, we provide a simple relation for the conditional…

Reducing circuit depth and identifying an optimal trade-off between circuit depth and width is crucial for successful quantum computation. In this context, midcircuit measurement and feedforward have been shown to significantly reduce the…

Quantum Physics · Physics 2025-06-03 Hyeonjun Yeo , Ha Eum Kim , IlKwon Sohn , Kabgyun Jeong

In this paper, we analyze the circuit complexity for preparing ground states of quantum many-body systems. In particular, how this complexity grows as the ground state approaches a quantum phase transition. We discuss different definitions…

Quantum Physics · Physics 2023-11-08 Sebastián Roca-Jerat , Teresa Sancho-Lorente , Juan Román-Roche , David Zueco

We study the concurrence of arbitrary multipartite mixed quantum states. An explicit lower bound of the concurrence is derived, which detects quantum entanglement of some states better than some separability criteria, and gives sufficient…

Quantum Physics · Physics 2009-11-13 Ming Li , Shao-Ming Fei , Zhi-XiWang

We address the question of minimal requirements for the existence of quantum bound states. In particular, we demonstrate that a few-body system with zero-range momentum-independent two-body interactions is unstable against decay into…

Nuclear Theory · Physics 2021-03-16 Martin Schäfer , Lorenzo Contessi , Johannes Kirscher , Jiří Mareš

We study the concurrence of four-qubit quantum states and provide analytical lower bounds of concurrence in terms of the monogamy inequality of concurrence for qubit systems. It is shown that these lower bounds are able to improve the…

Quantum Physics · Physics 2014-02-11 Xue-Na Zhu , Shao-Ming Fei

We investigate the fundamental time complexity, as constrained by Lieb-Robinson bounds, for preparing entangled states useful in quantum metrology. We relate the minimum time to the Quantum Fisher Information ($F_Q$) for a system of $N$…

We consider thermal relaxation process of a quantum system attached to a single or multiple reservoirs. Quantifying the degree of irreversibility by entropy production, we prove that the irreversibility of the thermal relaxation is…

Statistical Mechanics · Physics 2021-11-08 Tan Van Vu , Yoshihiko Hasegawa

While the ability to measure low temperatures accurately in quantum systems is important in a wide range of experiments, the possibilities and the fundamental limits of quantum thermometry are not yet fully understood theoretically. Here we…

Quantum Physics · Physics 2019-07-10 Patrick P. Potts , Jonatan Bohr Brask , Nicolas Brunner

We present a general sufficiency condition for the presence of multipartite entanglement in thermal states stemming from the ground state entanglement. The condition is written in terms of the ground state entanglement and the partition…

Quantum Physics · Physics 2008-02-13 Damian Markham , Janet Anders , Vlatko Vedral , Mio Murao , Akimasa Miyake