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High-fidelity single- and two-qubit gates are essential building blocks for a fault-tolerant quantum computer. While there has been much progress in suppressing single-qubit gate errors in superconducting qubit systems, two-qubit gates…

A major challenge for scaling up superconducting quantum computers is unwanted couplings between qubits, which lead to always-on ZZ couplings that impact gate fidelities by shifting energy levels conditional on qubit states. To tackle this…

Quantum Physics · Physics 2024-12-30 Simon Pettersson Fors , Jorge Fernández-Pendás , Anton Frisk Kockum

We introduce a superconducting qubit architecture that combines high-coherence qubits and tunable qubit-qubit coupling. With the ability to set the coupling to zero, we demonstrate that this architecture is protected from the frequency…

In superconducting quantum circuits, decoherence errors in qubits constitute a critical factor limiting quantum gate performance. To mitigate decoherence-induced gate infidelity, rapid implementation of quantum gates is essential. Here we…

Precise control of superconducting qubits is essential for advancing both quantum simulation and quantum error correction. Recently, transmon qubit systems employing the single-transmon coupler (STC) scheme have demonstrated high-fidelity…

Future quantum information processors require tunable coupling architectures that can produce high fidelity logical gates between two or more qubits. Parametric coupling is a powerful technique for generating tunable interactions between…

Quantum Physics · Physics 2024-10-08 X. Y. Jin , K. Cicak , Z. Parrott , S. Kotler , F. Lecocq , J. Teufel , J. Aumentado , E. Kapit , R. W. Simmonds

It is advantageous for any quantum processor to support different classes of two-qubit quantum logic gates when compiling quantum circuits, a property that is typically not seen with existing platforms. In particular, access to a gate set…

We propose a selective dynamical decoupling scheme on a chain of permanently coupled qubits with XX type interactions, which is capable of dynamically suppressing any coupling in the chain by applying sequences of local pulses to the…

Quantum Physics · Physics 2015-12-16 Holger Frydrych , Michael Marthaler , Gernot Alber

Implementing precise operations on quantum systems is one of the biggest challenges for building quantum devices in a noisy environment. Dynamical decoupling (DD) attenuates the destructive effect of the environmental noise, but so far it…

Quantum Physics · Physics 2015-06-16 Jingfu Zhang , Alexandre M. Souza , Frederico Dias Brandao , Dieter Suter

High-performance two-qubit gates have been reported with superconducting qubits coupled via a single-transmon coupler (STC). Most of them are implemented for qubits with a small detuning since reducing residual $ZZ$ coupling for highly…

Quantum Physics · Physics 2023-02-09 Kentaro Kubo , Hayato Goto

Tunable couplers in superconducting qubit architectures enable strong qubit-qubit interactions for two-qubit gates while suppressing unwanted coupling during single-qubit operations. However, achieving low error rates for fast two-qubit…

Quantum Physics · Physics 2026-04-08 Angela Q. Chen , Xian Wu , Sarah Strong , Stefano Poletto

Building a scalable universal high-performance quantum processor is a formidable challenge. In particular, the problem of realizing fast high-perfomance two-qubit gates of high-fidelity remains needful. Here we propose a building block for…

Demonstrating that logical qubits outperform their physical counterparts is a milestone for achieving reliable quantum computation. Here, we propose to protect logical qubits with a novel dynamical decoupling scheme that implements iSWAP…

Quantum Physics · Physics 2025-08-15 Jia-Xiu Han , Jiang Zhang , Guang-Ming Xue , Haifeng Yu , Guilu Long

Control of entanglement between qubits at distant quantum processors using a two-qubit gate is an essential function of a scalable, modular implementation of quantum computation. Among the many qubit platforms, spin qubits in silicon…

We explore the protection of quantum gates from arbitrary single- and two-qubit noises with properly designed dynamical decoupling pulses. The proposed dynamical decoupling method is a concatenation of a sequence of pulses formed by…

Quantum Physics · Physics 2024-05-08 Chunfeng Wu , Gangcheng Wang , Xun-Li Feng

Superconducting qubits are a promising candidate for building a quantum computer. A continued challenge for fast yet accurate gates to minimize the effects of decoherence. Here we apply numerical methods to design fast entangling gates,…

Quantum Physics · Physics 2015-06-16 D. J. Egger , F. K. Wilhelm

Kerr-cat qubits are a promising candidate for fault-tolerant quantum computers owing to the biased nature of their errors. The $ZZ$ coupling between the qubits can be utilized for a two-qubit entangling gate, but the residual coupling…

Quantum Physics · Physics 2024-01-23 Takaaki Aoki , Taro Kanao , Hayato Goto , Shiro Kawabata , Shumpei Masuda

To reduce circuit depth when executing Quantum algorithms, it is necessary to maximize qubit connectivity on a near-term quantum processor. While addressing this, we also need to ensure high gate fidelity, suppression of unwanted ZZ…

Quantum Physics · Physics 2026-02-09 Uday Sannigrahi , Amlan Chakrabarti , Swapnil Saha , Shrinjita Biswas

High-fidelity two-qubits gates are essential for the realization of large-scale quantum computation and simulation. Tunable coupler design is used to reduce the problem of parasitic coupling and frequency crowding in many-qubit systems and…