The Experts below are selected from a list of 37632 Experts worldwide ranked by ideXlab platform
Chu Guo - One of the best experts on this subject based on the ideXlab platform.
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Variational Quantum Circuits for Quantum state tomography
Physical Review A, 2020Co-Authors: Yong Liu, Shichuan Xue, Anqi Huang, Xiaogang Qiang, Heliang Huang, Mingtang Deng, Dongyang Wang, Chu GuoAbstract:Quantum state tomography is a key process in most Quantum experiments. In this work, we employ Quantum machine learning for state tomography. Given an unknown Quantum state, it can be learned by maximizing the fidelity between the output of a variational Quantum Circuit and this state. The number of parameters of the variational Quantum Circuit grows linearly with the number of qubits and the Circuit depth, so that only polynomial measurements are required, even for highly entangled states. After that, a subsequent classical Circuit simulator is used to transform the information of the target Quantum state from the variational Quantum Circuit into a familiar format. We demonstrate our method by performing numerical simulations for the tomography of the ground state of a one-dimensional Quantum spin chain, using a variational Quantum Circuit simulator. Our method is suitable for near-term Quantum computing platforms, and could be used for relatively large-scale Quantum state tomography for experimentally relevant Quantum states.
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general purpose Quantum Circuit simulator with projected entangled pair states and the Quantum supremacy frontier
Physical Review Letters, 2019Co-Authors: Chu Guo, Yong Liu, Min Xiong, Shichuan Xue, Anqi Huang, Xiaogang Qiang, Junhua Liu, Shenggen Zheng, Heliang Huang, Mingtang DengAbstract:Recent advances on Quantum computing hardware have pushed Quantum computing to the verge of Quantum supremacy. Here, we bring together many-body Quantum physics and Quantum computing by using a method for strongly interacting two-dimensional systems, the projected entangled-pair states, to realize an effective general-purpose simulator of Quantum algorithms. The classical computing complexity of this simulator is directly related to the entanglement generation of the underlying Quantum Circuit rather than the number of qubits or gate operations. We apply our method to study random Quantum Circuits, which allows us to quantify precisely the memory usage and the time requirements of random Quantum Circuits. We demonstrate our method by computing one amplitude for a $7\ifmmode\times\else\texttimes\fi{}7$ lattice of qubits with depth ($1+40+1$) on the Tianhe-2 supercomputer.
Franco Nori - One of the best experts on this subject based on the ideXlab platform.
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hybrid Quantum Circuit consisting of a superconducting flux qubit coupled to a spin ensemble and a transmission line resonator
Physical Review B, 2013Co-Authors: Zeliang Xiang, J Q You, Franco NoriAbstract:We propose an experimentally realizable hybrid Quantum Circuit for achieving a strong coupling between a spin ensemble and a transmission-line resonator via a superconducting flux qubit used as a data bus. The resulting coupling can be used to transfer Quantum information between the spin ensemble and the resonator. In particular, in contrast to the direct coupling without a data bus, our approach requires far less spins to achieve a strong coupling between the spin ensemble and the resonator (e.g., three to four orders of magnitude less). This proposed hybrid Quantum Circuit could enable a long-time Quantum memory when storing information in the spin ensemble, and allows the possibility to explore nonlinear effects in the ultrastrong-coupling regime.
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optical selection rules and phase dependent adiabatic state control in a superconducting Quantum Circuit
Physical Review Letters, 2005Co-Authors: Yuxi Liu, J Q You, L F Wei, C P Sun, Franco NoriAbstract:We analyze the optical selection rules of the microwave-assisted transitions in a flux qubit superconducting Quantum Circuit (SQC). We show that the parities of the states relevant to the superconducting phase in the SQC are well defined when the external magnetic flux Phi(e)=Phi(0)/2; then the selection rules are the same as the ones for the electric-dipole transitions in usual atoms. When Phi(e)not equal Phi(0)/2, the symmetry of the potential of the artificial "atom" is broken, a so-called Delta-type "cyclic" three-level atom is formed, where one- and two-photon processes can coexist. We study how the population of these three states can be selectively transferred by adiabatically controlling the electromagnetic field pulses. Different from Lambda-type atoms, the adiabatic population transfer in our three-level Delta atom can be controlled not only by the amplitudes but also by the phases of the pluses.
Takeshi Ohshima - One of the best experts on this subject based on the ideXlab platform.
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Hybrid Quantum Circuit with a superconducting qubit coupled to a spin ensemble
Physical Review Letters, 2011Co-Authors: Y Kubo, A. Dewes, N. Morishita, H. Abe, Shinobu Onoda, Junichi Isoya, Cécile Grezes, Tadashi Umeda, Hitoshi Sumiya, Takeshi OhshimaAbstract:We report the experimental realization of a hybrid Quantum Circuit combining a superconducting qubit and an ensemble of electronic spins. The qubit, of the transmon type, is coherently coupled to the spin ensemble consisting of nitrogen-vacancy centers in a diamond crystal via a frequency-tunable superconducting resonator acting as a Quantum bus. Using this Circuit, we prepare a superposition of the qubit states that we store into collective excitations of the spin ensemble and retrieve back into the qubit later on. These results constitute a proof of concept of spin-ensemble based Quantum memory for superconducting qubits.
Jingbo Wang - One of the best experts on this subject based on the ideXlab platform.
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combinatorial optimisation via highly efficient Quantum walks
arXiv: Quantum Physics, 2020Co-Authors: Samuel Marsh, Jingbo WangAbstract:We present a highly efficient Quantum Circuit for performing continuous time Quantum walks (CTQWs) over an exponentially large set of combinatorial objects, provided that the objects can be indexed efficiently. CTQWs form the core mixing operation of a generalised version of the Quantum Approximate Optimisation Algorithm, which works by `steering' the Quantum amplitude into high-quality solutions. The efficient Quantum Circuit holds the promise of finding high-quality solutions to certain classes of NP-hard combinatorial problems such as the Travelling Salesman Problem, maximum set splitting, graph partitioning, and lattice path optimisation.
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efficient Quantum walks over exponentially large sets of combinatorial objects for optimisation
arXiv: Quantum Physics, 2019Co-Authors: Samuel Marsh, Jingbo WangAbstract:We present a highly efficient Quantum Circuit for performing continuous time Quantum walks (CTQWs) over an exponentially large set of combinatorial objects, provided that they can be ranked and unranked efficiently. CTQWs form the core mixing operation of a generalised version of the Quantum Approximate Optimisation Algorithm, which works by 'steering' the Quantum amplitude into high-quality solutions. The efficient Quantum Circuit holds the promise of finding high-quality solutions to certain classes of NP-hard combinatorial problems such as the Travelling Salesman Problem, maximum set splitting, graph partitioning and lattice path optimisation.
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CUGatesDensity - Quantum Circuit analyser extended to density matrices
Computer Physics Communications, 2013Co-Authors: Trond Løke, Jingbo WangAbstract:Abstract CUGatesDensity is an extension of the original Quantum Circuit analyser CUGates (Loke and Wang, 2011) [7] to provide explicit support for the use of density matrices. The new package enables simulation of Quantum Circuits involving statistical ensemble of mixed Quantum states. Such analysis is of vital importance in dealing with Quantum decoherence, measurements, noise and error correction, and fault tolerant computation. Several examples involving mixed state Quantum computation are presented to illustrate the use of this package. Program summary Program title: CUGatesDensity.m Catalogue identifier: AEPY_v1_0 Program summary URL: http://cpc.cs.qub.ac.uk/summaries/AEPY_v1_0.html Program obtainable from: CPC Program Library, Queen’s University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 5368 No. of bytes in distributed program, including test data, etc.: 143994 Distribution format: tar.gz Programming language: Mathematica. Computer: Any computer installed with a copy of Mathematica 6.0 or higher. Operating system: Any system with a copy of Mathematica 6.0 or higher installed. Classification: 4.15. Nature of problem: To simulate arbitrarily complex Quantum Circuits comprised of single/multiple qubit and qudit Quantum gates with mixed state registers. Solution method: A density matrix representation for mixed states and a state vector representation for pure states are used. The construct is based on an irreducible form of matrix decomposition, which allows a highly efficient implementation of general controlled gates with multiple conditionals. Running time: The examples provided in the notebook CUGatesDensity.nb take approximately 30 s to run on a laptop PC.
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An efficient Quantum Circuit analyser on qubits and qudits
Computer Physics Communications, 2011Co-Authors: Trond Løke, Jingbo WangAbstract:Abstract This paper presents a highly efficient decomposition scheme and its associated Mathematica notebook for the analysis of complicated Quantum Circuits comprised of single/multiple qubit and qudit Quantum gates. In particular, this scheme reduces the evaluation of multiple unitary gate operations with many conditionals to just two matrix additions, regardless of the number of conditionals or gate dimensions. This improves significantly the capability of a Quantum Circuit analyser implemented in a classical computer. This is also the first efficient Quantum Circuit analyser to include qudit Quantum logic gates. Program summary Program title: CUGates.m Catalogue identifier: AEJM_v1_0 Program summary: URL: http://cpc.cs.qub.ac.uk/summaries/AEJM_v1_0.html Program obtainable from: CPC Program Library, Queenʼs University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 8168 No. of bytes in distributed program, including test data, etc.: 173 899 Distribution format: tar.gz Programming language: Mathematica Computer: Any computer installed with Mathematica 6.0 or higher. Operating system: Any system with a copy of Mathematica 6.0 or higher installed. Classification: 4.15 Nature of problem: The CUGates notebook simulates arbitrarily complex Quantum Circuits comprised of single/multiple qubit and qudit Quantum gates. Solution method: It utilizes an irreducible form of matrix decomposition for a general controlled gate with multiple conditionals and is highly efficient in simulating complex Quantum Circuits. Running time: Details of CPU time usage for various example runs are given in Section 4.
Yong Liu - One of the best experts on this subject based on the ideXlab platform.
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Variational Quantum Circuits for Quantum state tomography
Physical Review A, 2020Co-Authors: Yong Liu, Shichuan Xue, Anqi Huang, Xiaogang Qiang, Heliang Huang, Mingtang Deng, Dongyang Wang, Chu GuoAbstract:Quantum state tomography is a key process in most Quantum experiments. In this work, we employ Quantum machine learning for state tomography. Given an unknown Quantum state, it can be learned by maximizing the fidelity between the output of a variational Quantum Circuit and this state. The number of parameters of the variational Quantum Circuit grows linearly with the number of qubits and the Circuit depth, so that only polynomial measurements are required, even for highly entangled states. After that, a subsequent classical Circuit simulator is used to transform the information of the target Quantum state from the variational Quantum Circuit into a familiar format. We demonstrate our method by performing numerical simulations for the tomography of the ground state of a one-dimensional Quantum spin chain, using a variational Quantum Circuit simulator. Our method is suitable for near-term Quantum computing platforms, and could be used for relatively large-scale Quantum state tomography for experimentally relevant Quantum states.
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general purpose Quantum Circuit simulator with projected entangled pair states and the Quantum supremacy frontier
Physical Review Letters, 2019Co-Authors: Chu Guo, Yong Liu, Min Xiong, Shichuan Xue, Anqi Huang, Xiaogang Qiang, Junhua Liu, Shenggen Zheng, Heliang Huang, Mingtang DengAbstract:Recent advances on Quantum computing hardware have pushed Quantum computing to the verge of Quantum supremacy. Here, we bring together many-body Quantum physics and Quantum computing by using a method for strongly interacting two-dimensional systems, the projected entangled-pair states, to realize an effective general-purpose simulator of Quantum algorithms. The classical computing complexity of this simulator is directly related to the entanglement generation of the underlying Quantum Circuit rather than the number of qubits or gate operations. We apply our method to study random Quantum Circuits, which allows us to quantify precisely the memory usage and the time requirements of random Quantum Circuits. We demonstrate our method by computing one amplitude for a $7\ifmmode\times\else\texttimes\fi{}7$ lattice of qubits with depth ($1+40+1$) on the Tianhe-2 supercomputer.
