Realization of High-Fidelity Controlled-Phase Gates in Extensible Superconducting Qubits Design with a Tunable Coupler

High-fidelity two-qubit 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 manyqubit systems and thus thought to be advantageous. Here we design an extensible 5-qubit system in which center transmon qubit can couple to every four near-neighboring qubits via a capacitive tunable coupler and experimentally demonstrate high-fidelity controlled-phase(CZ) gate by manipulating central qubit and one nearneighboring qubit. Speckle purity benchmarking and cross entropy benchmarking are used to assess the purity fidelity and the fidelity of the CZ gate. The average purity fidelity of the CZ gate is 99.69±0.04% and the average fidelity of the CZ gate is 99.65±0.04%, which means that the control error is about 0.04%. Our work is helpful for resolving many challenges in implementation of large-scale quantum systems.

Realization of Fast All-Microwave Controlled-Z Gates with a Tunable Coupler

The development of high-fidelity two-qubit quantum gates is essential for digital quantum computing.Here,we propose and realize an all-microwave parametric controlled-Z(CZ)gates by coupling strength modulation in a superconducting Transmon qubit system with tunable couplers.After optimizing the design of the tunable coupler together with the control pulse numerically,we experimentally realized a 100 ns CZ gate with high fidelity of 99.38%±0.34%and the control error being 0.1%.We note that our CZ gates are not affected by pulse distortion and do not need pulse correction,providing a solution for the real-time pulse generation in a dynamic quantum feedback circuit.With the expectation of utilizing our all-microwave control scheme to reduce the number of control lines through frequency multiplexing in the future,our scheme draws a blueprint for the high-integrable quantum hardware design.

Progress in the diagnosis and treatment of graft fibrosis after liver transplantation

Liver transplantation(LT)is considered one of the best treatments for patients with end-stage liver diseases.However,some patients with no significant clinical manifestations or abnormal laboratory tests still experience graft fibrosis during postoperative follow-up,which is often recognized by graft histopathology.Graft fibrosis can lead to graft dysfunction,thereby reducing the survival time of the recipient and even requiring retransplantation.Currently,noninvasive methods are widely applied in the assessment of hepatic and allograft fibrosis.Although both noninvasive diagnostic models based on laboratory examination indicators and elastography technology that can quantify liver stiffness have some value in the evaluation of fibrosis,the diagnostic accuracy and characteristics of these various methods vary and cannot replace liver biopsy completely.In recent years,some liver-protective drugs and proprietary Chinese traditional medicines have been proven to delay or reverse chronic liver fibrosis.Nevertheless,their efficacy and safety for LT recipients need to be further verified.This article reviews the diagnosis and treatment of graft fibrosis after LT to provide a reference for improving the overall survival rate of LT recipients.

在61比特可编程超导量子处理器上对量子多体态进行量子神经元感知

对具有不同性质和物相的多体量子态进行分类是量子多体物理学中最基本的任务之一.然而,由于巨大数量的相互作用的粒子所产生的指数级的复杂性,大规模量子态的分类对于经典的方法来说极具挑战性.本文提出了一种新的方法,称为量子神经元感知.利用一个61比特的超导量子处理器作为演示,作者表明该方案可以有效地对两种不同类型的多体现象,即遍历相和局域相,进行分类.量子神经元感知过程使他们能够通过只测量一个量子比特来区分这些多体物相,并提供比传统方法(如测量不平衡度)更好的分辨率.本研究证明了量子神经元感知在近期量子处理器应用的可行性和扩展性,并为探索更大规模系统中的量子多体现象开辟了新的途径.

Quantum computational advantage via 60-qubit 24-cycle random circuit sampling

To ensure a long-term quantum computational advantage,the quantum hardware should be upgraded to withstand the competition of continuously improved classical algorithms and hardwares.Here,we demonstrate a superconducting quantum computing systems Zuchongzhi 2.1,which has 66 qubits in a two-dimensional array in a tunable coupler architecture.The readout fidelity of Zuchongzhi 2.1 is considerably improved to an average of 97.74%.The more powerful quantum processor enables us to achieve larger-scale random quantum circuit sampling,with a system scale of up to 60 qubits and 24 cycles,and fidelity of FXEB=(3·66±0·345)×10^(-4).The achieved sampling task is about 6 orders of magnitude more difficult than that of Sycamore[Nature 574,505(2019)]in the classic simulation,and 3 orders of magnitude more difficult than the sampling task on Zuchongzhi 2.0[arXiv:2106.14734(2021)].The time consumption of classically simulating random circuit sampling experiment using state-of-the-art classical algorithm and supercomputer is extended to tens of thousands of years(about 4·8×104years),while Zuchongzhi 2.1 only takes about 4.2 h,thereby significantly enhancing the quantum computational advantage.

Both APRI and FIB‐4 could effectively evaluate liver fibrosis in liver transplantation recipients

To the Editor,Liver transplantation(LT)is the only curative therapy for patients with end‐stage liver disease.1 Due to the high incidence of metabolic syndrome after LT,nonalcoholic fatty liver disease(NAFLD)has gradually become an essential cause of post‐LT fibrosis.2 Liver fibrosis can progress to liver cirrhosis and carries the risk of developing hepatocellular carcinoma(HCC),which adversely affects long‐term survival after LT.3,4 Early detection and active intervention for liver fibrosis after LT are crucial in LT recipients.Previous studies have confirmed that transient elastography(TE)could accurately detect liver fibrosis in LT recipients by comparing TE with liver biopsy.