High fidelity single shot qubit state readout is essential for many quantum information processing protocols. In superconducting quantum circuit, the qubit state is usually determined by detecting the dispersive frequ...High fidelity single shot qubit state readout is essential for many quantum information processing protocols. In superconducting quantum circuit, the qubit state is usually determined by detecting the dispersive frequency shift of a microwave cavity from either transmission or reflection. We demonstrate the use of constructive interference between the transmitted and reflected signal to optimize the qubit state readout, with which we find a better resolved state discrimination and an improved qubit readout fidelity. As a simple and convenient approach, our scheme can be combined with other qubit readout methods based on the discrimination of cavity photon states to further improve the qubit state readout.展开更多
A non-classical light source is essential for implementing a wide range of quantum information processing protocols,including quantum computing,networking,communication and metrology.In the microwave regime,propagatin...A non-classical light source is essential for implementing a wide range of quantum information processing protocols,including quantum computing,networking,communication and metrology.In the microwave regime,propagating photonic qubits,which transfer quantum information between multiple superconducting quantum chips,serve as building blocks for large-scale quantum computers.In this context,spectral control of propagating single photons is crucial for interfacing different quantum nodes with varied frequencies and bandwidths.Here a deterministic microwave quantum light source was demonstrated based on superconducting quantum circuits that can generate propagating single photons,time-bin encoded photonic qubits and qudits.In particular,the frequency of the emitted photons can be tuned in situ as large as 200 MHz.Even though the internal quantum efficiency of the light source is sensitive to the working fre-quency,it is shown that the fidelity of the propagating photonic qubit can be well preserved with the time-bin encoding scheme.This work thus demonstrates a versatile approach to realizing a practical quantum light source for future distributed quantum computing.展开更多
基金Supported by the Beijing Academy of Quantum Information Sciencethe Frontier Science Center for Quantum Information of the Ministry of Education of China through the Tsinghua University Initiative Scientific Research Program+3 种基金the National Natural Science Foundation of China (Grant No. 11874235)the National Key Research and Development Program of China (Grant Nos. 2016YFA0301902 and 2020YFA0309500)support from Shuimu Tsinghua Scholar Programthe International Postdoctoral Exchange Fellowship Program。
文摘High fidelity single shot qubit state readout is essential for many quantum information processing protocols. In superconducting quantum circuit, the qubit state is usually determined by detecting the dispersive frequency shift of a microwave cavity from either transmission or reflection. We demonstrate the use of constructive interference between the transmitted and reflected signal to optimize the qubit state readout, with which we find a better resolved state discrimination and an improved qubit readout fidelity. As a simple and convenient approach, our scheme can be combined with other qubit readout methods based on the discrimination of cavity photon states to further improve the qubit state readout.
基金supported by the Innovation Program for Quantum Science and Technology (2021ZD0301704)the Tsinghua Univer-sity Initiative Scientific Research Program,and the Ministry of Education of China.
文摘A non-classical light source is essential for implementing a wide range of quantum information processing protocols,including quantum computing,networking,communication and metrology.In the microwave regime,propagating photonic qubits,which transfer quantum information between multiple superconducting quantum chips,serve as building blocks for large-scale quantum computers.In this context,spectral control of propagating single photons is crucial for interfacing different quantum nodes with varied frequencies and bandwidths.Here a deterministic microwave quantum light source was demonstrated based on superconducting quantum circuits that can generate propagating single photons,time-bin encoded photonic qubits and qudits.In particular,the frequency of the emitted photons can be tuned in situ as large as 200 MHz.Even though the internal quantum efficiency of the light source is sensitive to the working fre-quency,it is shown that the fidelity of the propagating photonic qubit can be well preserved with the time-bin encoding scheme.This work thus demonstrates a versatile approach to realizing a practical quantum light source for future distributed quantum computing.
