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Recently, several groups have demonstrated two-qubit gate fidelities in semiconductor spin qubit systems above 99%. Achieving this regime of fault-tolerant compatible high fidelities is nontrivial and requires exquisite stability and…

Systematic errors in qubit state preparation arise due to non-idealities in the qubit control lines such as impedance mismatch. Using a data-based methodology of short-open-load calibration at a temperature of 30 mK, we report calibrated…

In the letter, we propose an anti-quantum-channel disturbance decoder for quantum key distribution (QKD). The decoder is based on a quarter-wave plate reflector-Michelson (Q-M) interferometer, with which the QKD system can be free of…

Quantum Physics · Physics 2019-06-26 Huaxing Xu , Shaohua Wang , Yang Huang , Yaqi Song , Changlei Wang

Frequency tunable qubit plays a significant role for scalable superconducting quantum processors. The state-of-the-art room-temperature electronics for tuning qubit frequency suffers from unscalable limit, such as heating problem, linear…

Superconducting qubits have been used in the most advanced demonstrations of quantum information processing, and they can be manufactured at-scale using proven semiconductor techniques. This makes them one of the leading technologies in the…

Pre-fault tolerant quantum computers have already demonstrated the ability to estimate observable values accurately, at a scale beyond brute-force classical computation. This has been enabled by error mitigation techniques that often rely…

A major challenge in operating multi-qubit quantum processors is to mitigate multi-qubit coherent errors. For superconducting circuits, besides crosstalk originating from imperfect isolation of control lines, dispersive coupling between…

We report the first experimental realization of a scalable basic cell for quantum routing, enabling coherent control and exchange of microwave photons between two spatially separated superconducting waveguides coupled via a single transmon…

Cat-state qubits (qubits encoded with cat states) have recently drawn intensive attention due to their enhanced life times with quantum error correction. We here propose a method to implement a universal controlled-phase gate of two…

Quantum Physics · Physics 2017-11-22 Yu Zhang , Xiong Zhao , Li Yu , Qi-Ping Su , Chui-Ping Yang

Achieving fast gates and long coherence times for superconducting qubits presents challenges, typically requiring either a stronger coupling of the drive line or an excessively strong microwave signal to the qubit. To address this, we…

Quantum Physics · Physics 2024-07-17 Aashish Sah , Suman Kundu , Heikki Suominen , Qiming Chen , Mikko Möttönen

In circuit quantum electrodynamics, measuring the state of a superconducting qubit introduces a loss channel which can enhance spontaneous emission through the Purcell effect, thus decreasing qubit lifetime. This decay can be mitigated by…

With the rapid scaling of superconducting quantum processors, electronic control systems relying on commercial off-the-shelf instruments face critical bottlenecks in signal density, power consumption, and crosstalk mitigation. Here we…

The \textit{heavy-fluxonium} circuit is a promising building block for superconducting quantum processors due to its long relaxation and dephasing time at the half-flux frustration point. However, the suppressed charge matrix elements and…

Qubit controllers are essential for scaling superconducting quantum processors, but implementing them at the 10 mK stage of a dilution refrigerator remains challenging due to stringent cooling constraints. Here we report an ultralow-power…

We propose a two-qubit collisional phase gate that can be implemented with available atom chip technology, and present a detailed theoretical analysis of its performance. The gate is based on earlier phase gate schemes, but uses a qubit…

In superconducting circuit quantum information technologies, classical microwave pulses are applied to control and measure the qubit states. Currently, the design of these microwave pulses use simple theoretical or numerical models that do…

Quantum Physics · Physics 2023-05-03 Thomas E. Roth , Samuel T. Elkin

Accurate control of quantum degrees of freedom is promising for sensing, communication, and computing, but building a useful quantum computer faces a central isolation-and-control challenge: qubits must remain well isolated from their…

Quantum Physics · Physics 2026-03-17 Aashish Sah , Suman Kundu , Priyank Singh , Eemeli Forsbom , Vasilii Vadimov , Mikko Möttönen

Qubits are the basic building blocks of a quantum processor which require electromagnetic pulses in giga hertz frequency range and latency in nanoseconds for control and readout. In this paper, we address three main challenges associated…

Kitaev's 0-$\pi $ qubit encodes quantum information in two protected, near-degenerate states of a superconducting quantum circuit. In a recent work, we have shown that the coherence times of a realistic 0-$\pi $ device can surpass that of…

Quantum Physics · Physics 2019-05-07 Agustin Di Paolo , Arne L. Grimsmo , Peter Groszkowski , Jens Koch , Alexandre Blais