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Dissipation engineering has attracted growing interest as an approach to controlling open quantum systems through engineered system-environment interactions. Standard variational quantum circuits are usually built from unitary operations…

Quantum Physics · Physics 2026-05-26 Yuan Yao , Ruipeng Xing , Yongjian Gu , Yiming Huang , Xiao Yuan

Quantum arithmetic computation requires a substantial number of scratch qubits to stay reversible. These operations necessitate qubit and gate resources equivalent to those needed for the larger of the input or output registers due to state…

Quantum Physics · Physics 2025-07-21 Omid Faizy , Norbert Wehn , Paul Lukowicz , Maximilian Kiefer-Emmanouilidis

Decoherence -- in the current physical implementations of quantum computers -- makes depth reduction a vital task in quantum-circuit design. Moore and Nilsson (SIAM Journal of Computing, 2001) demonstrated that additional qubits -- known as…

Quantum Physics · Physics 2022-09-26 Jiaqing Jiang , Xiaoming Sun , Shang-Hua Teng , Bujiao Wu , Kewen Wu , Jialin Zhang

Quantum computing is emerging as a new computational paradigm with the potential to transform several research fields, including quantum chemistry. However, current hardware limitations (including limited coherence times, gate infidelities,…

We improve the number of T gates needed to perform an n-bit adder from 8n + O(1) to 4n + O(1). We do so via a "temporary logical-AND" construction which uses four T gates to store the logical-AND of two qubits into an ancilla and zero T…

Quantum Physics · Physics 2018-06-21 Craig Gidney

Finding solid and practical quantum advantages via noisy quantum devices without error correction is a critical but challenging problem. Conversely, comprehending the fundamental limitations of the state-of-the-art is equally crucial. In…

Quantum Physics · Physics 2026-03-25 Yuxuan Yan , Zhenyu Du , Junjie Chen , Xiongfeng Ma

We extend the model of Ancilla Driven Quantum Computation (ADQC) by considering gates with arbitrary entangling power. By giving up stepwise determinism, universal QC can still be achieved through a variable length sequence of single qubit…

Quantum Physics · Physics 2013-03-11 Kerem Halil Shah , Daniel Kuan Li Oi

We present a scalable uniform technique for construction of highly conditional C$^n$-NOT quantum gates of trapped ion qubits, such as the Toffoli gate, without using ancilla states and circuits of an exorbitant number of concatenated one-…

Quantum Physics · Physics 2015-05-28 Svetoslav S. Ivanov , Nikolay V. Vitanov

Dynamic quantum circuits (DQCs) incorporate mid-circuit measurements and gates conditioned on these measurement outcomes. DQCs can prepare certain long-range entangled states in constant depth, making them a promising route to preparing…

Quantum Physics · Physics 2024-10-14 Faisal Alam , Bryan K. Clark

We introduce a family of quantized field states that can perform exact (entanglement- and error-free) rotations of a two-level atom starting from a specific state on the Bloch sphere. We discuss the similarities and differences between…

Quantum Physics · Physics 2024-10-03 Shanon Vuglar , Julio Gea-Banacloche

There is no unique way to encode a quantum algorithm into a quantum circuit. With limited qubit counts, connectivity, and coherence times, a quantum circuit optimization is essential to make the best use of near-term quantum devices. We…

A cost-effective n-bit Toffoli gate is proposed to be realized (or transpiled) based on the layouts (linear, T-like, and I-like) and the number of n physical qubits for IBM quantum computers. This proposed gate is termed the "layout-aware…

Quantum Physics · Physics 2024-10-18 Ali Al-Bayaty , Marek Perkowski

Quantum error correction (QEC) is essential for achieving fault-tolerant quantum computing. While superconducting qubits are among the most promising candidates for scalable QEC, their limited nearest-neighbor connectivity presents…

Motivated by realistic hardware considerations of the pre-fault-tolerant era, we comprehensively study the impact of uncorrected noise on quantum circuits. We first show that any noise `truncates' most quantum circuits to effectively…

The metrological ability of carefully designed probes can be spoilt by the presence of noisy processes occurring during their evolution. The noise is responsible for altering the evolution of the probes in such a way that bear little or no…

We introduce a new paradigm for quantum computing called Ancilla-Driven Quantum Computation (ADQC) combines aspects of the quantum circuit and the one-way model to overcome challenging issues in building large-scale quantum computers.…

Quantum Physics · Physics 2010-08-12 Elham Kashefi , Daniel K. L. Oi , Daniel E. Browne , Janet Anders , Erika Andersson

Several methods, known as Quantum Process Tomography, are available to characterize the evolution of quantum systems, a task of crucial importance. However, their complexity dramatically increases with the size of the system. Here we…

A defining feature in the field of quantum computing is the potential of a quantum device to outperform its classical counterpart for a specific computational task. By now, several proposals exist showing that certain sampling problems can…

Quantum Physics · Physics 2020-09-23 Rawad Mezher , Joe Ghalbouni , Joseph Dgheim , Damian Markham

Neutral atom arrays have become a promising platform for quantum computing, especially the field programmable qubit array (FPQA) endowed with the unique capability of atom movement. This feature allows dynamic alterations in qubit…

Quantum Physics · Physics 2024-09-13 Hanrui Wang , Daniel Bochen Tan , Pengyu Liu , Yilian Liu , Jiaqi Gu , Jason Cong , Song Han

Quantum computing allows for the manipulation of highly correlated states whose properties quickly go beyond the capacity of any classical method to calculate. Thus one natural problem which could lend itself to quantum advantage is the…

Quantum Physics · Physics 2024-12-19 Kevin Lively , Tim Bode , Jochen Szangolies , Jian-Xin Zhu , Benedikt Fauseweh