In quantum computation and quantum information processing, the manipulation and engineering of quantum systems to suit certain purposes are an ongoing task. One such example is quantum state transfer(QST), an essentia...In quantum computation and quantum information processing, the manipulation and engineering of quantum systems to suit certain purposes are an ongoing task. One such example is quantum state transfer(QST), an essential requirement for both quantum communication and large-scale quantum computation. Here we engineer a chain of four superconducting qubits with tunable couplers to realize the perfect state transfer(PST) protocol originally proposed in quantum spin networks and successfully demonstrate the efficient transfer of an arbitrary single-qubit state from one end of the chain to the other,achieving a high fidelity of 0.986 in just 25 ns. This demonstrated QST is readily to extend to larger chain and multi-node configurations, thus serving as a desirable tool for scalable quantum information processing.展开更多
High fidelity two-qubit gates are fundamental for scaling up the superconducting qubit number.We use two qubits coupled via a frequency-tunable coupler which can adjust the coupling strength,and demonstrate the CZ gat...High fidelity two-qubit gates are fundamental for scaling up the superconducting qubit number.We use two qubits coupled via a frequency-tunable coupler which can adjust the coupling strength,and demonstrate the CZ gate using two different schemes,adiabatic and diabatic methods.The Clifford based randomized benchmarking(RB) method is used to assess and optimize the CZ gate fidelity.The fidelities of adiabatic and diabatic CZ gates are 99.53(8)% and 98.72(2)%,respectively.We also analyze the errors induced by the decoherence.Comparing to 30 ns duration time of adiabatic CZ gate,the duration time of diabatic CZ gate is 19 ns,revealing lower incoherence error rate r’_(incoherent),int=0.0197(5) compared to r_(incoherent,int)=0.0223(3).展开更多
A tunable dual-broad-band branch-line coupler (BLC) utilizing composite right/left-handed (CRLH) transmission lines is presented. Two λ/4 segments consisting of CRLH transmission lines are added to each port to broad...A tunable dual-broad-band branch-line coupler (BLC) utilizing composite right/left-handed (CRLH) transmission lines is presented. Two λ/4 segments consisting of CRLH transmission lines are added to each port to broaden the dual bands of the branch-line coupler. Numerical simulation and optimal design of the novel coupler are presented. The dual bands of the novel coupler are tunable and broad. The 1-dB bandwidth of each pass band is more than 16% of the central frequency.展开更多
The muhimode interference （MMI） couplers, which operate at 1. 55 microns in deep rib InGaAsP/InP waveguide with large lateral confinement and tunable power splitting ratios, are of high interest in integrated optics...The muhimode interference （MMI） couplers, which operate at 1. 55 microns in deep rib InGaAsP/InP waveguide with large lateral confinement and tunable power splitting ratios, are of high interest in integrated optics. The gold contacts are applied on the top of waveguides where tuning is desired and the plasma effect will lead to negative refractive index change. The three-dimensional （3D） finite difference beam propagation method（FD-BPM） is used to model the tunable MMI couplers. The length of a 2 × 2 overlap-MMI is determined by FD-BPM, so the longitudinal position of tuning spots is obtained. The position of gold contacts with two types, the edge-pads or center-pad, are also determined. In our design, the length of MMI is 180 microns. If the width of pads is 50 microns and the refractive index is tuned from 0 to -0. 027, the power ratio is tuned from 50 ： 50 to the maximum 88.5 ： 11.4. For deep rib structure, the effective index（EI） method can not be used to simplify the 3D waveguide to plane waveguide because of its lower precision, and so the direct 3D FD-BPM simulation is necessary for the design of 3D MMI couplers.展开更多
An ultracompact,bandwidth-tunable filter has been demonstrated using a silicon-on-insulator(SOI)wafer.The device is based on cascaded grating-assisted contra-directional couplers(GACDCs).It also involves the use of a ...An ultracompact,bandwidth-tunable filter has been demonstrated using a silicon-on-insulator(SOI)wafer.The device is based on cascaded grating-assisted contra-directional couplers(GACDCs).It also involves the use of a subwavelength grating(SWG)structure.By heating one of the heaters on GACDCs,a bandwidth tunability of~6 nm is achieved.Owing to the benefit of having a large coupling coefficient between SWG and strip waveguides,the length of the coupling region is only 100 pm.Moreover,the combination of the curved SWG and the tapered strip waveguides effectively suppresses the sidelobes.The filter possesses features of simultaneous wavelength tuning with no free spectral range(FSR)limitation.A maximum bandwidth of 10 nm was experimentally measured with a high out-of-band contrast of 25 dB.Similarly,the minimum bandwidth recorded is 4 nm with an out-of-band contrast of 15 dB.展开更多
We propose and demonstrate a novel single-longitudinal-mode(SLM) erbium-doped fiber laser(EDFL) capable of operating at fixed-wavelength lasing mode with a tunable range more than 54 nm, an ultra-narrow linewidth of 4...We propose and demonstrate a novel single-longitudinal-mode(SLM) erbium-doped fiber laser(EDFL) capable of operating at fixed-wavelength lasing mode with a tunable range more than 54 nm, an ultra-narrow linewidth of 473 Hz and an ultra-high optical signal-to-noise ratio(OSNR) more than 72 dB, or operating at wavelength-swept mode with tunable sweep rate of 10—200 Hz and a sweep range more than 50 nm. The excellent features mainly benefit from a triple-ring subring cavity constructed by three optical couplers nested one another and a fiber Fabry-Pérot tunable filter which can be driven by a constant voltage or a periodic sweep voltage for fixed or wavelength-swept operation, respectively. The proposed EDFL has potential applications in high-resolution spectroscopy and fiber optic sensing.展开更多
A switchable dual-wavelength erbium-doped fiber laser(EDFL) with tunable wavelength is demonstrated. The ring cavity consists of two branches with a fiber Bragg grating(FBG) and a spherical-shape structure as fiber fi...A switchable dual-wavelength erbium-doped fiber laser(EDFL) with tunable wavelength is demonstrated. The ring cavity consists of two branches with a fiber Bragg grating(FBG) and a spherical-shape structure as fiber filters, respectively. By adjusting the variable optical attenuator(VOA), the laser can be switched between the single-wavelength mode and the dual-wavelength mode. The spherical-shape structure has good sensitivity to the temperature. When the temperature changes from 30 °C to 190 °C, the central wavelength of the EDFL generated by the branch of spherical-shape structure varies from 1 551.6 nm to 1 561.8 nm, which means that the wavelength interval is tunable.展开更多
We proposed a two-coupled microsphere resonator structure as the element of angular velocity sensing under the Sagnac effect.We analyzed the theoretical model of the two coupled microspheres,and derived the coupled-re...We proposed a two-coupled microsphere resonator structure as the element of angular velocity sensing under the Sagnac effect.We analyzed the theoretical model of the two coupled microspheres,and derived the coupled-resonatorinduced transparency（CRIT） transfer function,the effective phase shift,and the group delay.Experiments were also carried out to demonstrate the CRIT phenomenon in the two-coupled microsphere resonator structure.We calculated that the group index of the two-coupled sphere reaches n_g = 180.46,while the input light at a wavelength of 1550 nm.展开更多
A continuously tunable microwave photonic notch filter with complex coefficient based on phase modulation is proposed and demonstrated. The complex coefficient is generated using a Fourier-domain optical processor(FD-...A continuously tunable microwave photonic notch filter with complex coefficient based on phase modulation is proposed and demonstrated. The complex coefficient is generated using a Fourier-domain optical processor(FD-OP) to control the amplitude and phase of the optical carrier and radio-frequency(RF) phase modulation sidebands. By controlling the FD-OP,the frequency response of the filter can be tuned in the full free spectral range(FSR) without changing the shape and the FSR of the frequency response. The results show that the center frequency of the notch filter can be continuously tuned from 17.582 GHz to 29.311 GHz with FSR of 11.729 GHz. The shape of the frequency response keeps unchanged when the phase is tuned.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 12034018 and 11625419)。
文摘In quantum computation and quantum information processing, the manipulation and engineering of quantum systems to suit certain purposes are an ongoing task. One such example is quantum state transfer(QST), an essential requirement for both quantum communication and large-scale quantum computation. Here we engineer a chain of four superconducting qubits with tunable couplers to realize the perfect state transfer(PST) protocol originally proposed in quantum spin networks and successfully demonstrate the efficient transfer of an arbitrary single-qubit state from one end of the chain to the other,achieving a high fidelity of 0.986 in just 25 ns. This demonstrated QST is readily to extend to larger chain and multi-node configurations, thus serving as a desirable tool for scalable quantum information processing.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11890704,12004042,and 11674376)the Natural Science Foundation of Beijing,China(Grant No.Z190012)+1 种基金the National Key Research and Development Program of China(Grant No.2016YFA0301800)the Key-Area Research and Development Program of Guang-Dong Province,China(Grant No.2018B030326001)。
文摘High fidelity two-qubit gates are fundamental for scaling up the superconducting qubit number.We use two qubits coupled via a frequency-tunable coupler which can adjust the coupling strength,and demonstrate the CZ gate using two different schemes,adiabatic and diabatic methods.The Clifford based randomized benchmarking(RB) method is used to assess and optimize the CZ gate fidelity.The fidelities of adiabatic and diabatic CZ gates are 99.53(8)% and 98.72(2)%,respectively.We also analyze the errors induced by the decoherence.Comparing to 30 ns duration time of adiabatic CZ gate,the duration time of diabatic CZ gate is 19 ns,revealing lower incoherence error rate r’_(incoherent),int=0.0197(5) compared to r_(incoherent,int)=0.0223(3).
基金Project (No. 2004CB719802) supported by the National Basic Re-search Program (973) of China
文摘A tunable dual-broad-band branch-line coupler (BLC) utilizing composite right/left-handed (CRLH) transmission lines is presented. Two λ/4 segments consisting of CRLH transmission lines are added to each port to broaden the dual bands of the branch-line coupler. Numerical simulation and optimal design of the novel coupler are presented. The dual bands of the novel coupler are tunable and broad. The 1-dB bandwidth of each pass band is more than 16% of the central frequency.
文摘The muhimode interference （MMI） couplers, which operate at 1. 55 microns in deep rib InGaAsP/InP waveguide with large lateral confinement and tunable power splitting ratios, are of high interest in integrated optics. The gold contacts are applied on the top of waveguides where tuning is desired and the plasma effect will lead to negative refractive index change. The three-dimensional （3D） finite difference beam propagation method（FD-BPM） is used to model the tunable MMI couplers. The length of a 2 × 2 overlap-MMI is determined by FD-BPM, so the longitudinal position of tuning spots is obtained. The position of gold contacts with two types, the edge-pads or center-pad, are also determined. In our design, the length of MMI is 180 microns. If the width of pads is 50 microns and the refractive index is tuned from 0 to -0. 027, the power ratio is tuned from 50 ： 50 to the maximum 88.5 ： 11.4. For deep rib structure, the effective index（EI） method can not be used to simplify the 3D waveguide to plane waveguide because of its lower precision, and so the direct 3D FD-BPM simulation is necessary for the design of 3D MMI couplers.
基金This work was supported in part by the National Key R&D Program of China(No.2019YFB2203101)in part by the National Natural Science Foundation of China(Grant Nos.61805137 and 61835008)+2 种基金in part by the Natural Science Foundation of Shanghai,China(No.19ZR1475400)Shanghai Sailing Program(No.18YF1411900)Open Project Program of Wuhan National Laboratory for Optoelectronics(No.2018WNLOKF012).
文摘An ultracompact,bandwidth-tunable filter has been demonstrated using a silicon-on-insulator(SOI)wafer.The device is based on cascaded grating-assisted contra-directional couplers(GACDCs).It also involves the use of a subwavelength grating(SWG)structure.By heating one of the heaters on GACDCs,a bandwidth tunability of~6 nm is achieved.Owing to the benefit of having a large coupling coefficient between SWG and strip waveguides,the length of the coupling region is only 100 pm.Moreover,the combination of the curved SWG and the tapered strip waveguides effectively suppresses the sidelobes.The filter possesses features of simultaneous wavelength tuning with no free spectral range(FSR)limitation.A maximum bandwidth of 10 nm was experimentally measured with a high out-of-band contrast of 25 dB.Similarly,the minimum bandwidth recorded is 4 nm with an out-of-band contrast of 15 dB.
基金supported by the Natural Science Foundation of Hebei Province(No.F2016201023)the Technology Foundation for Selected Overseas Chinese Scholar of Ministry of Human Resources and Social Security of China(No.CG2015003006)the Advanced Talents Program of Hebei Educational Committee(No.GCC2014020)
文摘We propose and demonstrate a novel single-longitudinal-mode(SLM) erbium-doped fiber laser(EDFL) capable of operating at fixed-wavelength lasing mode with a tunable range more than 54 nm, an ultra-narrow linewidth of 473 Hz and an ultra-high optical signal-to-noise ratio(OSNR) more than 72 dB, or operating at wavelength-swept mode with tunable sweep rate of 10—200 Hz and a sweep range more than 50 nm. The excellent features mainly benefit from a triple-ring subring cavity constructed by three optical couplers nested one another and a fiber Fabry-Pérot tunable filter which can be driven by a constant voltage or a periodic sweep voltage for fixed or wavelength-swept operation, respectively. The proposed EDFL has potential applications in high-resolution spectroscopy and fiber optic sensing.
基金supported by the National High Technology Research and Development Program of China(No.2013AA014201)the Tianjin Youth Science Foundation(No.13JCQNJC01800)
文摘A switchable dual-wavelength erbium-doped fiber laser(EDFL) with tunable wavelength is demonstrated. The ring cavity consists of two branches with a fiber Bragg grating(FBG) and a spherical-shape structure as fiber filters, respectively. By adjusting the variable optical attenuator(VOA), the laser can be switched between the single-wavelength mode and the dual-wavelength mode. The spherical-shape structure has good sensitivity to the temperature. When the temperature changes from 30 °C to 190 °C, the central wavelength of the EDFL generated by the branch of spherical-shape structure varies from 1 551.6 nm to 1 561.8 nm, which means that the wavelength interval is tunable.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.51225504,61171056,and 91123036)the Program for the Top Young Academic Leaders of Higher Learning Institutions of Shanxi Province,China
文摘We proposed a two-coupled microsphere resonator structure as the element of angular velocity sensing under the Sagnac effect.We analyzed the theoretical model of the two coupled microspheres,and derived the coupled-resonatorinduced transparency（CRIT） transfer function,the effective phase shift,and the group delay.Experiments were also carried out to demonstrate the CRIT phenomenon in the two-coupled microsphere resonator structure.We calculated that the group index of the two-coupled sphere reaches n_g = 180.46,while the input light at a wavelength of 1550 nm.
基金supported by the National High Technology Research and Development Program of China(863 Program)(No.2013AA014200)the National Natural Science Foundation of China(No.11444001)the Municipal Natural Science Foundation of Tianjin in China(No.14JCYBJC16500)
文摘A continuously tunable microwave photonic notch filter with complex coefficient based on phase modulation is proposed and demonstrated. The complex coefficient is generated using a Fourier-domain optical processor(FD-OP) to control the amplitude and phase of the optical carrier and radio-frequency(RF) phase modulation sidebands. By controlling the FD-OP,the frequency response of the filter can be tuned in the full free spectral range(FSR) without changing the shape and the FSR of the frequency response. The results show that the center frequency of the notch filter can be continuously tuned from 17.582 GHz to 29.311 GHz with FSR of 11.729 GHz. The shape of the frequency response keeps unchanged when the phase is tuned.
文摘本文提出了一种功率比可重构平衡正交耦合器,宽功率比调节范围由两个可调电容实现。所有调节状态下的差模响应、共模抑制和差模-共模转化抑制同时实现。为验证,设计并加工了一个中心频率2 GHz的功率比可重构平衡耦合器,采用ZNBT8矢量网络分析仪测试S参数,测试结果与仿真结果吻合良好。测试功率比范围为-11.3~10.2 d B,所有状态下差模回波损耗和隔离度均大于15 dB。
