Phase-coherent multi-tone lasers play a critical role in atomic,molecular,and optical physics.Among them,the Raman opeartion laser for manipulating atomic hyperfine qubits requires gigahertz bandwidth and low phase no...Phase-coherent multi-tone lasers play a critical role in atomic,molecular,and optical physics.Among them,the Raman opeartion laser for manipulating atomic hyperfine qubits requires gigahertz bandwidth and low phase noise to retain long-term coherence.Raman operation lasers generated by directly modulated and frequency-multipled infrared lasers are compact and stable but lack feedback control to actively suppress the phase noise,which limits their performance in practical applications.In this work,we employ a fiber electro-optical modulator driven by a voltage-controlled oscillator(VCO)to modulate a monochromatic laser and employ a second-harmonic generation process to convert it to the visible domain,where the beat note of the Raman operation laser is stabilized by controlling the output frequency of VCO with a digital phase-locked loop(PLL).The low-frequency phase noise is effectively suppressed compared to the scheme without active feedback and it reaches-80 d Bc/Hz@5 k Hz with a 20 k Hz loop bandwidth.Furthermore,this compact and robust scheme effectively reduces the system's complexity and cost,which is promising for extensive application in atomic,molecular,and optical physics.展开更多
Since 2005, there has been a huge growth in the use of engineered control pulses to perform desired quantum operations in systems such as nuclear magnetic resonance quantum information processors. These approaches, wh...Since 2005, there has been a huge growth in the use of engineered control pulses to perform desired quantum operations in systems such as nuclear magnetic resonance quantum information processors. These approaches, which build on the original gradient ascent pulse engineering algorithm, remain computationally intensive because of the need to calculate matrix exponentials for each time step in the control pulse. In this study, we discuss how the propagators for each time step can be approximated using the Trotter-Suzuki formula, and a further speedup achieved by avoiding unnecessary operations. The resulting procedure can provide substantial speed gain with negligible costs in the propagator error, providing a more practical approach to pulse en-ineerinK.展开更多
In this work, for understanding bio-information transmission through long distance a type of nonlinear master equation is studied. We found that the nonlinear power term can introduce a novel solution of the equation,...In this work, for understanding bio-information transmission through long distance a type of nonlinear master equation is studied. We found that the nonlinear power term can introduce a novel solution of the equation, in which a possible invariant structure as an information soliton can exist when time elapses long enough. This provides a sort of constructive channel for bio-information transmission for long distance.展开更多
In this paper, we characterize the saturation of four universal inequalities in quantum information theory, including a variant version of strong subadditivity inequality for von Neumann entropy, the coherent informat...In this paper, we characterize the saturation of four universal inequalities in quantum information theory, including a variant version of strong subadditivity inequality for von Neumann entropy, the coherent information inequality, the Holevo quantity, and average entropy inequalities. These results shed new light on quantum information inequalities.展开更多
For a pure non-markovian dephasing model we derive analytic expressions of coherent information,quantum discord,and entanglement.We find that for the cases of the initial Werner states,the dynamical behavior of cohere...For a pure non-markovian dephasing model we derive analytic expressions of coherent information,quantum discord,and entanglement.We find that for the cases of the initial Werner states,the dynamical behavior of coherent information is similar to that of quantum discord but different from that of entanglement.Coherent information,as well as quantum discord,can reveal the quantum correlations in some mixed-states,in which the entanglement is zero.展开更多
基金supported by the National Key Research and Development Program of China(No.2017YFA0304100)National Natural Science Foundation of China(Nos.11774335,11734015,and 12204455)+1 种基金the Key Research Program of Frontier Sciences,CAS(No.QYZDY-SSWSLH003)Innovation Program for Quantum Science and Technology(Nos.2021ZD0301604 and 2021ZD0301200)。
文摘Phase-coherent multi-tone lasers play a critical role in atomic,molecular,and optical physics.Among them,the Raman opeartion laser for manipulating atomic hyperfine qubits requires gigahertz bandwidth and low phase noise to retain long-term coherence.Raman operation lasers generated by directly modulated and frequency-multipled infrared lasers are compact and stable but lack feedback control to actively suppress the phase noise,which limits their performance in practical applications.In this work,we employ a fiber electro-optical modulator driven by a voltage-controlled oscillator(VCO)to modulate a monochromatic laser and employ a second-harmonic generation process to convert it to the visible domain,where the beat note of the Raman operation laser is stabilized by controlling the output frequency of VCO with a digital phase-locked loop(PLL).The low-frequency phase noise is effectively suppressed compared to the scheme without active feedback and it reaches-80 d Bc/Hz@5 k Hz with a 20 k Hz loop bandwidth.Furthermore,this compact and robust scheme effectively reduces the system's complexity and cost,which is promising for extensive application in atomic,molecular,and optical physics.
文摘Since 2005, there has been a huge growth in the use of engineered control pulses to perform desired quantum operations in systems such as nuclear magnetic resonance quantum information processors. These approaches, which build on the original gradient ascent pulse engineering algorithm, remain computationally intensive because of the need to calculate matrix exponentials for each time step in the control pulse. In this study, we discuss how the propagators for each time step can be approximated using the Trotter-Suzuki formula, and a further speedup achieved by avoiding unnecessary operations. The resulting procedure can provide substantial speed gain with negligible costs in the propagator error, providing a more practical approach to pulse en-ineerinK.
文摘In this work, for understanding bio-information transmission through long distance a type of nonlinear master equation is studied. We found that the nonlinear power term can introduce a novel solution of the equation, in which a possible invariant structure as an information soliton can exist when time elapses long enough. This provides a sort of constructive channel for bio-information transmission for long distance.
基金Supported by National Natural Science Foundation of China under Grant Nos.11301124,11171301the Doctoral Programs Foundation of Ministry of Education of China under Grant No.J20130061
文摘In this paper, we characterize the saturation of four universal inequalities in quantum information theory, including a variant version of strong subadditivity inequality for von Neumann entropy, the coherent information inequality, the Holevo quantity, and average entropy inequalities. These results shed new light on quantum information inequalities.
基金Supported by National Science Foundation of China under Grant Nos. 11005008,10974016,and 11075013
文摘For a pure non-markovian dephasing model we derive analytic expressions of coherent information,quantum discord,and entanglement.We find that for the cases of the initial Werner states,the dynamical behavior of coherent information is similar to that of quantum discord but different from that of entanglement.Coherent information,as well as quantum discord,can reveal the quantum correlations in some mixed-states,in which the entanglement is zero.
