Control of a Josephson Digital Phase Detector via an SFQ-Based Flux Bias Driver

Abstract: Quantum computation requires high-fidelity qubit readout, preserving the quantum state. In the case of superconductings qubits, readout is typically performed using a complex analog experimental setup operating at room temperature, which poses significant technological and economic barriers to large system scalability. An alternative approach is to perform a cryogenic on-chip qubit readout based on […]

Cryo-CMOS Bias-Voltage Generation and Demultiplexing at mK Temperatures for Large-Scale Arrays of Quantum Devices

Abstract: The rapidly growing number of qubits in semiconductor quantum computers requires a scalable control interface, including the efficient generation of dc bias voltages for gate electrodes. To avoid unrealistically complex wiring between any room-temperature electronics and the cryogenic qubits, this article presents an integrated cryogenic solution for the bias-voltage generation and distribution for large-scale […]

Improved Belief Propagation Decoding Algorithms for Surface Codes

Abstract: Quantum error correction is crucial for universal fault-tolerant quantum computing. Highly accurate and low-time-complexity decoding algorithms play an indispensable role in ensuring quantum error correction works effectively. Among existing decoding algorithms, belief propagation (BP) is notable for its nearly linear time complexity and general applicability to stabilizer codes. However, BP’s decoding accuracy without postprocessing […]

Memory-Optimized Cubic Splines for High-Fidelity Quantum Operations

Abstract: Radio frequency pulses are preponderant for the control of quantum bits and the execution of operations in quantum computers. The ability to fine-tune key pulse parameters, such as time-dependent amplitude, phase, and frequency, is essential to achieve maximal gate fidelity and mitigate errors. As systems increase in scale, a larger proportion of the control […]

Q-Gen: A Parameterized Quantum Circuit Generator

Abstract: Unlike most classical algorithms that take an input and give the solution directly as an output, quantum algorithms produce a quantum circuit that works as an indirect solution to computationally hard problems. In the full quantum computing workflow, most data processing remains in the classical domain except for running the quantum circuit in the […]

Analysis of Parameterized Quantum Circuits: On the Connection Between Expressibility and Types of Quantum Gates

Abstract: Expressibility is a crucial factor of a parameterized quantum circuit (PQC). In the context of variational-quantum-algorithm-based quantum machine learning (QML), a QML model composed of a highly expressible PQC and a sufficient number of qubits is theoretically capable of approximating any arbitrary continuous function. While much research has explored the relationship between expressibility and […]

Reducing Quantum Error Correction Overhead With Versatile Flag-Sharing Syndrome Extraction Circuits

Abstract: Given that quantum error correction processes are unreliable, an efficient error syndrome extraction circuit should use fewer ancillary qubits, quantum gates, and measurements while maintaining low circuit depth, to minimize the circuit area, roughly defined as the product of circuit depth and the number of physical qubits. We propose to design parallel flagged syndrome […]

Quantum Wavelength-Division Multiplexing and Multiple-Access Communication Systems and Networks: Advanced Applications

Abstract: A cost-effective global quantum Internet may be developed using the existing communication infrastructure. This article examines the quantum version of three conventional wavelength-division-multiplexing and multiple-access (WDM) communication systems and networks. They are Lambdanet-based broadcast WDM networks, quantum routers based on a waveguide grating router, and fiber-to-the-quantum nodes that are fed by two opposing and […]

Three-Party Controlled Authentication Semiquantum Key Agreement Protocol for Online Joint Consultation

Abstract: In Wise Information Technology of Medicine, to ensure both confidentiality and integrity of the data created during online joint consultations, and to solve the problem that ordinary users cannot afford expensive quantum devices and are vulnerable to man-in-the-middle attacks during communication, this article proposes a three-party controlled authentication semiquantum key agreement protocol, leveraging the […]

Modeling and Performance Evaluation of Hybrid Classical–Quantum Serverless Computing Platforms

Abstract: While quantum computing technologies are evolving toward achieving full maturity, hybrid algorithms, such as variational quantum computing, are already emerging as valid candidates to solve practical problems in fields, such as chemistry and operations research. This situation calls for a tighter and better integration of classical and quantum computing infrastructures to improve efficiency and […]