We employ quantum state and process tomography with time-bin qubits to benchmark a city-wide metropolitan quantum communication system.Over this network,we implement real-time feedback control systems for stabilizing ...We employ quantum state and process tomography with time-bin qubits to benchmark a city-wide metropolitan quantum communication system.Over this network,we implement real-time feedback control systems for stabilizing the phase of the time-bin qubits and obtain a 99.3%quantum process fidelity to the ideal channel,indicating the high quality of the whole quantum communication system.This allows us to implement a field trial of high-performance quantum key distribution using coherent one way protocol with an average quantum bit error rate and visibility of 0.25%and 99.2%during 12 h over 61 km.Our results pave the way for the high-performance quantum network with metropolitan fibers.展开更多
Nonadiabatic holonomic quantum computation has received increasing attention due to its robustness against control errors. However, all the previous schemes have to use at least two sequentially implemented gates to r...Nonadiabatic holonomic quantum computation has received increasing attention due to its robustness against control errors. However, all the previous schemes have to use at least two sequentially implemented gates to realize a general one-qubit gate. Based on two recent reports, we construct two Hamiltonians and experimentally realized nonadiabatic holonomic gates by a single-shot implementation in a two-qubit nuclear magnetic resonance （NMR） system. Two noncommuting one-qubit holonomic gates, rotating along .~ and ~ axes respectively, are implemented by evolving a work qubit and an ancillary qubit nonadiabatically following a quantum circuit designed. Using a sequence compiler developed for NMR quantum information processor, we optimize the whole pulse sequence, minimizing the total error of the implementation. Finally, all the nonadiabatic holonomic gates reach high unattenuated experimental fidelities over 98%.展开更多
基金supported by the National Key Research and Development Program of China(Nos.2017YFA0303704 and 2019YFA0308704)the National Natural Science Foundation of China(Nos.11674170,11690032,and 11804153)+4 种基金NSFC-BRICS(No.61961146001)the Natural Science Foundation of Jiangsu Province(No.BK20170010)the Leading-edge Technology Program of Jiangsu Natural Science Foundation(BK20192001)the program for Innovative Talents and Entrepreneur in Jiangsuthe Fundamental Research Funds for the Central Universities。
文摘We employ quantum state and process tomography with time-bin qubits to benchmark a city-wide metropolitan quantum communication system.Over this network,we implement real-time feedback control systems for stabilizing the phase of the time-bin qubits and obtain a 99.3%quantum process fidelity to the ideal channel,indicating the high quality of the whole quantum communication system.This allows us to implement a field trial of high-performance quantum key distribution using coherent one way protocol with an average quantum bit error rate and visibility of 0.25%and 99.2%during 12 h over 61 km.Our results pave the way for the high-performance quantum network with metropolitan fibers.
基金supported by the National Natural Science Foundation of China(Grant Nos.91221205,and 11474181)the National Basic Research Program of China(Grants No.2015CB921002)
文摘Nonadiabatic holonomic quantum computation has received increasing attention due to its robustness against control errors. However, all the previous schemes have to use at least two sequentially implemented gates to realize a general one-qubit gate. Based on two recent reports, we construct two Hamiltonians and experimentally realized nonadiabatic holonomic gates by a single-shot implementation in a two-qubit nuclear magnetic resonance （NMR） system. Two noncommuting one-qubit holonomic gates, rotating along .~ and ~ axes respectively, are implemented by evolving a work qubit and an ancillary qubit nonadiabatically following a quantum circuit designed. Using a sequence compiler developed for NMR quantum information processor, we optimize the whole pulse sequence, minimizing the total error of the implementation. Finally, all the nonadiabatic holonomic gates reach high unattenuated experimental fidelities over 98%.
