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Quantum processing units boost entanglement at the level of hardware and enable physical simulations of highly correlated electron states in molecules and intermolecular chemical bonds. The variational quantum eigensolver provides a…

A scalable quantum computer could be built by networking together many simple processor cells, thus avoiding the need to create a single complex structure. The difficulty is that realistic quantum links are very error prone. A solution is…

Quantum Physics · Physics 2013-04-26 Naomi H. Nickerson , Ying Li , Simon C. Benjamin

Matrix product states (MPS) are a central language for one-dimensional quantum matter and a practical target for near-term quantum simulators and variational algorithms. Yet, while substantial effort has focused on preparing MPS with…

Quantum Physics · Physics 2026-04-21 Hyunho Cha , Subin Kim , Jungwoo Lee

Simulating noisy quantum circuits is vital in designing and verifying quantum algorithms in the current NISQ (Noisy Intermediate-Scale Quantum) era, where quantum noise is unavoidable. However, it is much more inefficient than the classical…

Quantum Physics · Physics 2023-11-27 Mingyu Huang , Ji Guan , Wang Fang , Mingsheng Ying

Quantum state purification is crucial in quantum communication and computation, aiming to recover a purified state from multiple copies of an unknown noisy state. This work introduces a general state purification framework designed to…

Quantum Physics · Physics 2024-09-27 Hongshun Yao , Yu-Ao Chen , Erdong Huang , Kaichu Chen , Honghao Fu , Xin Wang

Implementing many important sub-circuits on near-term quantum devices remains a challenge due to the high levels of noise and the prohibitive depth on standard nearest-neighbour topologies. Overcoming these barriers will likely require…

Quantum Physics · Physics 2024-11-06 Angus Mingare , Anastasia Moroz , Marcell D Kovacs , Andrew G Green

Quantum computation has been growing rapidly in both theory and experiments. In particular, quantum computing devices with a large number of qubits have been developed by IBM, Google, IonQ, and others. The current quantum computing devices…

Quantum Physics · Physics 2021-02-10 Rishabh Gupta , Rongxin Xia , Raphael D. Levine , Sabre Kais

This is a set of lectures on tensor networks with a strong emphasis on the core algorithms involving Matrix Product States (MPS) and Matrix Product Operators (MPO). Compared to other presentations, particular care has been given to…

Quantum Physics · Physics 2026-01-07 Xavier Waintal , Chen-How Huang , Christoph W. Groth

We present a scheme for implementing quantum operations with superconducting qubits. Our approach uses a "coupler" qubit to mediate a controllable, secular interaction between "data" qubits, pulse sequences which strongly mitigate the…

Quantum Physics · Physics 2013-10-22 Andrew J. Kerman , William D. Oliver

Quantum information processing tasks require exotic quantum states as a prerequisite. They are usually prepared with many different methods tailored to the specific resource state. Here we provide a versatile unified state preparation…

Quantum Physics · Physics 2021-01-18 Tanjung Krisnanda , Sanjib Ghosh , Tomasz Paterek , Timothy C. H. Liew

Quantum state purification is the functionality that, given multiple copies of an unknown state, outputs a state with increased purity. This will be an essential building block for near- and middle-term quantum ecosystems before the…

Quantum Physics · Physics 2024-06-14 Bo Yang , Elham Kashefi , Dominik Leichtle , Harold Ollivier

Quantum computers are inherently affected by noise. While in the long-term error correction codes will account for noise at the cost of increasing physical qubits, in the near-term the performance of any quantum algorithm should be tested…

In the current NISQ (Noisy Intermediate-Scale Quantum) era, simulating and verifying noisy quantum circuits is crucial but faces challenges such as quantum state explosion and complex noise representations, constraining simulation and…

Quantum Physics · Physics 2025-12-12 Mingyu Huang , Ji Guan , Wang Fang , Mingsheng Ying

Quantum computers hold promise to enable efficient simulations of the properties of molecules and materials; however, at present they only permit ab initio calculations of a few atoms, due to a limited number of qubits. In order to harness…

Materials Science · Physics 2020-07-07 He Ma , Marco Govoni , Giulia Galli

Simulating the topological phases of matter in synthetic quantum simulators is a topic of considerable interest. Given the universality of digital quantum simulators, the prospect of digitally simulating exotic topological phases is greatly…

Quantum Physics · Physics 2020-10-21 Feng Mei , Qihao Guo , Ya-Fei Yu , Liantuan Xiao , Shi-Liang Zhu , Suotang Jia

Entanglement purification protocols are fundamental primitives in quantum communication, enabling the distillation of high-quality entanglement using only local operations and classical communication. For large multipartite states, however,…

Quantum Physics · Physics 2026-04-06 Katerina Stloukalova , Jorge Miguel-Ramiro , Wolfgang Dür , Julius Wallnöfer

Matrix product purifications (MPPs) are a very efficient tool for the simulation of strongly correlated quantum many-body systems at finite temperatures. When a system features symmetries, these can be used to reduce computation costs…

Strongly Correlated Electrons · Physics 2018-02-15 Thomas Barthel

Due to the unreliability and limited capacity of existing quantum computer prototypes, quantum circuit simulation continues to be a vital tool for validating next generation quantum computers and for studying variational quantum algorithms,…

Quantum Physics · Physics 2021-04-01 Yipeng Huang , Steven Holtzen , Todd Millstein , Guy Van den Broeck , Margaret Martonosi

It is known that if the quantum gates in a proposed quantum computer are so noisy that they are incapable of generating entanglement, then the device can be efficiently simulated classically. If the measurements and single particle…

Quantum Physics · Physics 2012-01-04 N. Ratanje , S. Virmani

We study the use of entanglement purification for quantum communication over long distances. For distances much longer than the coherence length of a corresponding noisy quantum channel, the fidelity of transmission is usually so low that…

Quantum Physics · Physics 2008-12-18 W. Dür , H. - J. Briegel , J. I. Cirac , P. Zoller