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Code switching is an established technique that facilitates a universal set of FT quantum gate operations by combining two QEC codes with complementary sets of gates, which each by themselves are easy to implement fault-tolerantly. In this…

Quantum Physics · Physics 2025-09-10 Sascha Heußen , Janine Hilder

Superconducting qubits offer an unprecedentedly high degree of flexibility in terms of circuit encoding and parameter choices. However, in designing the qubit parameters one typically faces the conflicting goals of long coherence times and…

Quantum Physics · Physics 2025-04-08 C. A. Siegele , A. A. Sokolova , L. N. Kapoor , F. Hassani , J. M. Fink

Hybrids consisting of macroscopic superconducting circuits and microscopic components, such as atoms and spins, have the potential of transmitting an arbitrary state between different quantum species, leading to the prospective of…

We propose a nanoscale device consisting of a double quantum dot with strong intra- and inter- dot Coulomb repulsions. In this design, the current can only flow through the lower dot, but is triggered by the gate-controlled occupancy of the…

Mesoscale and Nanoscale Physics · Physics 2021-01-08 Pierre Lombardo , Roland Hayn , Denis Zhuravel , Steffen Schäfer

Singlet-triplet qubits in lateral quantum dots in semiconductor heterostructures exhibit high-fidelity single-qubit gates via exchange interactions and magnetic field gradients. High-fidelity two-qubit entangling gates are challenging to…

Mesoscale and Nanoscale Physics · Physics 2017-12-06 M. A. Wolfe , F. A. Calderon-Vargas , J. P. Kestner

We experimentally studied the switching off processes in the double-resonator coupler superconducting quantum circuit. In both frequency and time-domain, we observed the variation of qubit-qubit effective coupling by tuning the frequency…

Quantum Physics · Physics 2026-02-26 Hui Wang , Rui Wang , Daichi Sugiyama , Chih-Yao Shih , Ching-Yeh Chen , Hiroto Mukai , Hang Xue , J. S. Tsai

Transistors are key elements for enabling computational hardware in both classical and quantum domains. Here, we propose a voltage-gated spin transistor using itinerant electrons in the Hubbard model which acts at the level of single…

Quantum Physics · Physics 2021-12-03 Rozhin Yousefjani , Sougato Bose , Abolfazl Bayat

Continuously parameterized two-qubit gates are a key feature of state-of-the-art trapped-ion quantum processors as they have favorable error scalings and show distinct improvements in circuit performance over more restricted maximally…

In circuit-based quantum computing, the available gate set typically consists of single-qubit gates acting on each individual qubit and at least one entangling gate between pairs of qubits. In certain physical architectures, however, some…

Quantum Physics · Physics 2022-09-23 M. Pechal , G. Salis , M. Ganzhorn , D. J. Egger , M. Werninghaus , S. Filipp

Coherently dressed spins have shown promising results as building blocks for future quantum computers owing to their resilience to environmental noise and their compatibility with global control fields. This mode of operation allows for…

The power of a quantum circuit is determined through the number of two-qubit entangling gates that can be performed within the coherence time of the system. In the absence of parallel quantum gate operations, this would make the quantum…

Quantum Physics · Physics 2021-05-26 Rozhin Yousefjani , Abolfazl Bayat

We realize a device allowing for tunable and switchable coupling between two superconducting resonators mediated by an artificial atom. For the latter, we utilize a persistent current flux qubit. We characterize the tunable and switchable…

We propose a new way of implementing several elementary quantum gates for qubits in the coherent state basis. The operations are probabilistic and employ single photon subtractions as the driving force. Our schemes for single-qubit phase…

Quantum Physics · Physics 2015-05-19 Petr Marek , Jaromir Fiurasek

Parallel operations are important for both near-term quantum computers and larger-scale fault-tolerant machines because they reduce execution time and qubit idling. We propose and implement a pairwise-parallel gate scheme on a trapped-ion…

We introduce the paradigm of replacement-type quantum gates. This type of gate introduces input qubits, candidate qubits, and output qubits. The candidate qubits are prepared such, that a displacement conditional on the input qubit results…

Quantum Physics · Physics 2026-02-24 Florian Ginzel , Javad Kazemi , Valentin Torggler , Wolfgang Lechner

Non-adiabatic two-qubit gate proposals for trapped-ion systems offer superior performance and flexibility over adiabatic schemes at the cost of increased laser control requirements. Existing fast gate schemes are limited by single-qubit…

Superconducting circuits are highly controllable platforms to manipulate quantum states, which make them particularly promising for quantum information processing. We here show how the existence of a distance-independent interaction between…

Quantum Physics · Physics 2023-09-20 Pedro Rosario , Alan C. Santos , Celso Jorge Villas-Boas , Romain Bachelard

Superconducting quantum circuits typically use capacitive charge-based linear coupling schemes to control interactions between elements such as qubits. While simple and effective, this coupling scheme makes it difficult to satisfy competing…

Quantum Physics · Physics 2026-02-04 Gihwan Kim , Andreas Butler , Oskar Painter

Quantum error correction is a crucial tool for mitigating hardware errors in quantum computers by encoding logical information into multiple physical qubits. However, no single error-correcting code allows for an intrinsically…

We demonstrate that in a coupled two-qubit system any single-qubit gate can be decomposed into two conditional two-qubit gates and that any conditional two-qubit gate can be implemented by a manipulation analogous to that used for a…

Quantum Physics · Physics 2009-11-11 Zhongyuan Zhou , Shih-I Chu , Siyuan Han