From the perspective of state-channel interaction,standard quantum teleportation can be viewed as a communication process characterized by both input and output,functioning as a quantum depolarizing channel.To achieve...From the perspective of state-channel interaction,standard quantum teleportation can be viewed as a communication process characterized by both input and output,functioning as a quantum depolarizing channel.To achieve a precise quantification of the quantumness introduced by this channel,we examine its uncertainties,which encompass both statedependent and state-independent uncertainties.Specifically,for qudit systems,we provide general formulas for these uncertainties.We analyze the uncertainties associated with standard quantum teleportation when induced by isotropic states,Werner states,and X-states,and we elucidate the correlation between these uncertainties and the parameters of the specific mixed states.Our findings demonstrate the validity of quantifying these uncertainties.展开更多
For applying the perfect code to transmit quantum information over a noise channel,the standard protocol contains four steps:the encoding,the noise channel,the error-correction operation,and the decoding.In present wo...For applying the perfect code to transmit quantum information over a noise channel,the standard protocol contains four steps:the encoding,the noise channel,the error-correction operation,and the decoding.In present work,we show that this protocol can be simplified.The error-correction operation is not necessary if the decoding is realized by the so-called complete unitary transformation.We also offer a quantum circuit,which can correct the arbitrary single-qubit errors.展开更多
We report a metrology scheme which measures the magnetic susceptibility of an atomic spin ensemble along the x and z directions and produces parameter estimation with precision beating the standard quantum limit.The a...We report a metrology scheme which measures the magnetic susceptibility of an atomic spin ensemble along the x and z directions and produces parameter estimation with precision beating the standard quantum limit.The atomic ensemble is initialized via one-axis spin squeezing with optimized squeezing time and parameterΦ(to be estimated)assumed as uniformly distributed between 0 and 2πwhile fixed in each estimation.One estimation ofΦcan be produced with every two magnetic susceptibility data measured along the two axes respectively,which has an imprecision scaling(1.43±0.02)/N^(0.687±0.003)with respect to the number N of the atomic spins.The measurement scheme is easy to implement and is robust against the measurement fluctuation caused by environment noise and measurement defects.展开更多
A rubidium-beam microwave clock, optically pumped by a distributed feedback diode laser, is experimentally investigated. The clock is composed of a physical package, optical systems, and electric servo loops. The phys...A rubidium-beam microwave clock, optically pumped by a distributed feedback diode laser, is experimentally investigated. The clock is composed of a physical package, optical systems, and electric servo loops. The physical package realizes the microwave interrogation of a rubidium-atomic beam. The optical systems, equipped with two 780-nm distributed feedback laser diodes, yield light for pumping and detecting. The servo loops control the frequency of a local oscillator with respect to the microwave spectrum. With the experimental systems, the microwave spectrum, which has an amplitude of 4 n A and a line width of 700 Hz, is obtained. Preliminary tests show that the clock short-term frequency stability is 7 × 10^-11 at 1 s, and 3 × 10^-12 at 1000 s. These experimental results demonstrate the feasibility of the scheme for a manufactured clock.展开更多
A photon-number-resolving LiDAR approach and an active photon-number-filtering algorithm are proposed and demonstrated.This opens a new avenue for the development of single-photon LiDAR and relevant techniques to scie...A photon-number-resolving LiDAR approach and an active photon-number-filtering algorithm are proposed and demonstrated.This opens a new avenue for the development of single-photon LiDAR and relevant techniques to scientific study and real-world applications.展开更多
The sensitivity of optical measurement is ultimately constrained by the shot noise to the standard quantum limit.It has become a common concept that beating this limit requires quantum resources.A deep-learning neural...The sensitivity of optical measurement is ultimately constrained by the shot noise to the standard quantum limit.It has become a common concept that beating this limit requires quantum resources.A deep-learning neural network free of quantum principle has the capability of removing classical noise from images,but it is unclear in reducing quantum noise.In a coincidence-imaging experiment,we show that quantum-resource-free deep learning can be exploited to surpass the standard quantum limit via the photon-number-dependent nonlinear feedback during training.Using an effective classical light with photon flux of about 9×10^(4) photons per second,our deep-learning-based scheme achieves a 14 dB improvement in signal-to-noise ratio with respect to the standard quantum limit.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.12201300).
文摘From the perspective of state-channel interaction,standard quantum teleportation can be viewed as a communication process characterized by both input and output,functioning as a quantum depolarizing channel.To achieve a precise quantification of the quantumness introduced by this channel,we examine its uncertainties,which encompass both statedependent and state-independent uncertainties.Specifically,for qudit systems,we provide general formulas for these uncertainties.We analyze the uncertainties associated with standard quantum teleportation when induced by isotropic states,Werner states,and X-states,and we elucidate the correlation between these uncertainties and the parameters of the specific mixed states.Our findings demonstrate the validity of quantifying these uncertainties.
文摘For applying the perfect code to transmit quantum information over a noise channel,the standard protocol contains four steps:the encoding,the noise channel,the error-correction operation,and the decoding.In present work,we show that this protocol can be simplified.The error-correction operation is not necessary if the decoding is realized by the so-called complete unitary transformation.We also offer a quantum circuit,which can correct the arbitrary single-qubit errors.
基金supported by the National Natural Science Foundation of China(Grant Nos.T2121001,11934018,and U1801661)Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDB28000000)+2 种基金the Key-Area Research and Development Program of GuangDong Province,China(Grant No.2018B030326001)Guangdong Provincial Key Laboratory(Grant No.2019B121203002)the Science,Technology and Innovation Commission of Shenzhen Municipality(Grant Nos.KYTDPT20181011104202253 and 2016ZT06D348)。
文摘We report a metrology scheme which measures the magnetic susceptibility of an atomic spin ensemble along the x and z directions and produces parameter estimation with precision beating the standard quantum limit.The atomic ensemble is initialized via one-axis spin squeezing with optimized squeezing time and parameterΦ(to be estimated)assumed as uniformly distributed between 0 and 2πwhile fixed in each estimation.One estimation ofΦcan be produced with every two magnetic susceptibility data measured along the two axes respectively,which has an imprecision scaling(1.43±0.02)/N^(0.687±0.003)with respect to the number N of the atomic spins.The measurement scheme is easy to implement and is robust against the measurement fluctuation caused by environment noise and measurement defects.
基金Project supported by the National Natural Science Foundation of China(Grant No.11174015)
文摘A rubidium-beam microwave clock, optically pumped by a distributed feedback diode laser, is experimentally investigated. The clock is composed of a physical package, optical systems, and electric servo loops. The physical package realizes the microwave interrogation of a rubidium-atomic beam. The optical systems, equipped with two 780-nm distributed feedback laser diodes, yield light for pumping and detecting. The servo loops control the frequency of a local oscillator with respect to the microwave spectrum. With the experimental systems, the microwave spectrum, which has an amplitude of 4 n A and a line width of 700 Hz, is obtained. Preliminary tests show that the clock short-term frequency stability is 7 × 10^-11 at 1 s, and 3 × 10^-12 at 1000 s. These experimental results demonstrate the feasibility of the scheme for a manufactured clock.
文摘A photon-number-resolving LiDAR approach and an active photon-number-filtering algorithm are proposed and demonstrated.This opens a new avenue for the development of single-photon LiDAR and relevant techniques to scientific study and real-world applications.
基金supported by the National Key R&D Program of China(Nos.2019YFA0308700,2019YFA0308704,and 2022YFA1405000)the Innovation Program for Quantum Science and Technology(No.2021ZD0301400)+3 种基金the National Natural Science Foundation of China(Nos.11874212 and 11890704)the Program for Innovative Talents and Teams in Jiangsu(No.JSSCTD202138)the Excellent Research Program of Nanjing University(No.ZYJH002)the Natural Science Foundation of Jiangsu Province,Major Project(No.BK20212004).
文摘The sensitivity of optical measurement is ultimately constrained by the shot noise to the standard quantum limit.It has become a common concept that beating this limit requires quantum resources.A deep-learning neural network free of quantum principle has the capability of removing classical noise from images,but it is unclear in reducing quantum noise.In a coincidence-imaging experiment,we show that quantum-resource-free deep learning can be exploited to surpass the standard quantum limit via the photon-number-dependent nonlinear feedback during training.Using an effective classical light with photon flux of about 9×10^(4) photons per second,our deep-learning-based scheme achieves a 14 dB improvement in signal-to-noise ratio with respect to the standard quantum limit.
