The extremely local electric field enhancement and light confinement is demonstrated in dielectri... more The extremely local electric field enhancement and light confinement is demonstrated in dielectric waveguide with corner and gap geometry. The numerical results reveal the local electric field enhancement in the vicinity of the apex of fan-shaped waveguide. Classical electromagnetic theory predicts that the field enhancement and confinement abilities increase with decreasing radius of rounded corner (r) and gap (g), and show singularity for infinitesimal r and g. For practical parameters with r = g = 10 nm, the mode area of opposing apex-to-apex fan-shaped waveguides can be as small as 4 × 10 −3 A0 (A0 = λ 2 /4), far beyond the diffraction limit. This way of breaking diffraction limit with no loss outperforms plasmonic waveguides, where light confinement is realized at the cost of huge intrinsic loss in the metal. Furthermore, we propose a structure with dielectric bow-tie antenna on a silicon-on-insulator waveguide, whose field enhancement increases by one order. The lossless dielectric corner and gap structures offer an alternative method to enhance the light-matter interaction without metal nano-structure, and will find applications in quantum electrodynamics, sensors and nano-particle trapping.
ABSTRACT In two-component Bose-Einstein condensates, the one-axis twisting Hamiltonian leads to s... more ABSTRACT In two-component Bose-Einstein condensates, the one-axis twisting Hamiltonian leads to spin squeezing with a limitation that scales with the number of atoms as ${N}^{$-${}2/3}$. We propose a scheme to transform the one-axis twisting Hamiltonian into a two-axis twisting Hamiltonian, resulting in enhanced spin squeezing proportional to ${N}^{$-${}1}$ approaching the Heisenberg limit. Instead of pulse sequences, only one continuous driving field is required to realize such a transformation, thus the scheme is promising for experimental realization of a two-axis twisting Hamiltonian. Quantum information processing and quantum metrology may benefit from this method in the future.
A scheme to achieve spin squeezing using a geometric phase induced by a single mechanical mode is... more A scheme to achieve spin squeezing using a geometric phase induced by a single mechanical mode is proposed. The analytical and numerical results show that the ultimate degree of spin squeezing depends on the parameter n th +1/2 Q √ N , which is the ratio between the thermal excitation, the quality factor and square root of ensemble size. The undesired coupling between the spin ensemble and the bath can be efficiently suppressed by Bang-Bang control pulses. With high quality factor, the ultimate limit of the ideal one-axis twisting spin squeezing can be obtained for an NV ensemble in diamond.
Light is usually confined in photonic structures with a band gap or relatively high refractive in... more Light is usually confined in photonic structures with a band gap or relatively high refractive index for broad scientific and technical applications. Here, a light confinement mechanism is proposed based on the photonic bound state in the continuum (BIC). In a low-refractive-index waveguide on a highrefractive-index thin membrane, optical dissipation is forbidden because of the destructive interference of various leakage channels. The BIC-based low-mode-area waveguide and high-Q microresonator can be used to enhance light-matter interaction for laser, nonlinear optical and quantum optical applications. For example, a polymer structure on a diamond membrane shows excellent optical performance that can be achieved with large fabrication tolerance. It can induce strong coupling between photons and the nitrogen-vacancy center in diamond for scalable quantum information processors and networks.
Science China Physics, Mechanics & Astronomy, 2015
ABSTRACT In an optomechanical resonator, the optical and mechanical excitations can be coherently... more ABSTRACT In an optomechanical resonator, the optical and mechanical excitations can be coherently converted, which induces a transparency window for a weak probe laser beam. Here, we report an experimental study of transient optomechanically induced transparency (OMIT) using the silica microsphere with the breathing modes. The transient OMIT behavior obtained are in good agreement with theoretical calculations. In addition, the coherent interconversion between optical and mechanical excitations that can be used for light storage and readout has also been studied here. Our experimental results indicate that the light storage is closely related to the process of OMIT, and the photon-phonon conversion can be further applied to optical wavelength or optical mode conversion.
A dielectric body couples with electromagnetic fields through radiation pressure and electrostric... more A dielectric body couples with electromagnetic fields through radiation pressure and electrostrictive forces, which mediate phonon-photon coupling in cavity optomechanics. In a magnetic medium, according to the Korteweg-Helmholtz formula, which describes the electromagnetic force density acting on a medium, magneostrictive forces should arise and lead to phonon-magnon interaction. We report such a coupled phonon-magnon system based on ferrimagnetic spheres, which we term as cavity magnomechanics, by analogy to cavity optomechanics. Coherent phonon-magnon interactions, including electromagnetically induced transparency and absorption, are demonstrated. Because of the strong hybridization of magnon and microwave photon modes and their high tunability, our platform exhibits new features including parametric amplification of magnons and phonons, triple-resonant photon-magnon-phonon coupling, and phonon lasing. Our work demonstrates the fundamental principle of cavity magnomechanics and ...
Journal of the American Chemical Society, Jan 5, 2016
Nanoscale lasers are ideal light signal sources for integrated photonic devices. Most of the pres... more Nanoscale lasers are ideal light signal sources for integrated photonic devices. Most of the present lasers made of dielectric materials are restricted to being larger than half the wavelength of the optical field. Plasmon lasers made from metallic nanostructures can help to break the diffraction limit, yet they suffer from low optical pump efficiency and low quality factors. Integrating dielectric lasers with plasmonic waveguides to construct hybrid material systems may circumvent these problems and combine the advantages of both components. Here, we demonstrate the output of dielectric lasers at subwavelength scale via photon-plasmon coupling in rationally designed perovskite/silver heterostructures. The perovskite crystals offer the gain and high-Q cavity for low threshold laser generation while the embedded silver nanowires (AgNWs) help to output the lasing modes efficiently in the form of surface plasmons. The output coupling can be modulated by controlling the resonant modes o...
2012 7th IEEE International Conference on Nano/Micro Engineered and Molecular Systems (NEMS), 2012
Whispering gallery modes" (WGM) optical micro-and nano resonators are important category in nanop... more Whispering gallery modes" (WGM) optical micro-and nano resonators are important category in nanophotonics researches. The ultra-high quality factor (Q) makes them promising ranging from sensors, filters to low threshold sources. In the above supplications, the frequency stability of the WGM is critical, which is determined by several factors. In this paper, using the microsphere resonator we construct a robust packaged microsphere-taper coupling system (MTCS) to stabilize the resonant WGMs. Furthermore, a stable frequency references platform based on the packaged microcavity unit is constructed. This stable frequency references platform can eliminate the noise of the WGM, and promote the microresonator researches.
Extensive efforts have been expended in developing hybrid quantum systems to overcome the short c... more Extensive efforts have been expended in developing hybrid quantum systems to overcome the short coherence time of superconducting circuits by introducing the naturally long-lived spin degree of freedom. Among all the possible materials, single-crystal yttrium iron garnet has shown up recently as a promising candidate for hybrid systems, and various highly coherent interactions, including strong and even ultrastrong coupling, have been demonstrated. One distinct advantage in these systems is that spins form well-defined magnon modes, which allows flexible and precise tuning. Here we demonstrate that by dissipation engineering, a non-Markovian interaction dynamics between the magnon and the microwave cavity photon can be achieved. Such a process enables us to build a magnon gradient memory to store information in the magnon dark modes, which decouple from the microwave cavity and thus preserve a long lifetime. Our findings provide a promising approach for developing long-lifetime, mul...
A transient and high sensitivity sensor based on high-Q microcavity is proposed and studied theor... more A transient and high sensitivity sensor based on high-Q microcavity is proposed and studied theoretically. There are two ways to realize the transient sensor: monitor the spectrum by fast scanning of probe laser frequency or monitor the transmitted light with fixed laser frequency. For both methods, the non-equilibrium response not only tells the ultrafast environment variance, but also enable higher sensitivity. As examples of application, the transient sensor for nanoparticles adhering and passing by the microcavity is studied. It's demonstrated that the transient sensor can sense coupling region, external linear variation together with the speed and the size of a nanoparticle. We believe that our researches will open a door to the fast dynamic sensing by microcavity.
A photonic integrated circuit (PIC) is the optical analogy of an electronic loop in which photons... more A photonic integrated circuit (PIC) is the optical analogy of an electronic loop in which photons are signal carriers with high transport speed and parallel processing capability. Besides the most frequently demonstrated silicon-based circuits, PICs require a variety of materials for light generation, processing, modulation, and detection. With their diversity and flexibility, organic molecular materials provide an alternative platform for photonics; however, the versatile fabrication of organic integrated circuits with the desired photonic performance remains a big challenge. The rapid development of flexible electronics has shown that a solution printing technique has considerable potential for the large-scale fabrication and integration of microsized/nanosized devices. We propose the idea of soft photonics and demonstrate the function-directed fabrication of high-quality organic photonic devices and circuits. We prepared size-tunable and reproducible polymer microring resonators ...
We propose a new approach to realize all-optical circulator based on stimulated Brillouin scatter... more We propose a new approach to realize all-optical circulator based on stimulated Brillouin scattering in an integrated microresonator. Stimulated Brillouin scattering is a basic interaction between photon and traveling acoustic wave resulted from electrostriction and photoelastic effects. Due to the phase-matching requirement, the circulating acoustic wave can only couple to probe light which propagating along or opposite to the pump laser direction, thus exhibits a non-reciprocal phase shift. Combined with Mach-Zehnder interferometer, the optical circulator can be realized. Though the bandwidth is relatively small because of the narrow-band nature of microresonator, this magnetic-free all-optical integrated circulator may be applied for future on-chip photonic information processing.
We develop an architecture for distributed quantum computation using quantum bus of plasmonic cir... more We develop an architecture for distributed quantum computation using quantum bus of plasmonic circuits and spin qubits in self-assembled quantum dots. Deterministic quantum gates between two distant spin qubits can be reached by using an adiabatic approach in which quantum dots couple with highly detuned plasmon modes in a metallic nanowire. Plasmonic quantum bus offers a robust and scalable platform for quantum optics experiments and the development of on-chip quantum networks composed of various quantum nodes, such as quantum dots, molecules and nanoparticles.
The mechanism of unidirectional emission of high Q Whispering Gallery mode in deformed circular m... more The mechanism of unidirectional emission of high Q Whispering Gallery mode in deformed circular micro- cavities is studied and firstly presented in this paper. In phase space, light in the chaotic sea leaks out the cavity through the refraction regions, whose positions are controlled by stable islands. Moreover, the positions of fixed points according to the critical line in unstable manifolds mainly determines the light leak out from which refraction region and the direction of the emission. By controlling the cavity shape, we can tune the leaky regions, as well as the positions of fixed points, to achieve unidirectional emission high Q cavities with narrow angular divergence both in high and low refractive index mater
We propose to use efficient quantum error correcting codes with multilevel systems to protect enc... more We propose to use efficient quantum error correcting codes with multilevel systems to protect encoded quantum information from erasure errors and efficient implementation to repetitively correct these errors. Our scheme makes use of quantum polynomial codes to encode quantum information and generalizes teleportation based error correction for multilevel systems to repetitively correct photon erasures and operation errors. We discuss the application of our scheme for one-way quantum repeaters and discuss their physical implementation using atom mediated multiqubit gates.
In two-component BEC, the one-axis twisting Hamiltonian leads to spin squeezing with the limitati... more In two-component BEC, the one-axis twisting Hamiltonian leads to spin squeezing with the limitation that scales with the number of atoms as $N^{-\frac{2}{3}}$. We propose a scheme to transform the one-axis twisting Hamiltonian into a two-axis twisting Hamiltonian, resulting in enhanced spin squeezing $\propto N^{-1}$ approaching the Heisenberg limit. Instead of pulse sequences, only one continuous driving field is required to realizing such transforming, thus the scheme is promising for experiment realizations, to an one-axis twisting Hamiltonian. Quantum information processing and quantum metrology may benefit from this method in the future.
A new method based on the boundary element method (BEM) is developed to calculate high quality fa... more A new method based on the boundary element method (BEM) is developed to calculate high quality factors of whispering-gallery modes by studying the Poynting vector. The method has high calculation accuracy, which exceeds traditional methods with the same PC computation resource. To demonstrate the feasibility of the present method, circular and quadrupole microcavities are investigated with this method and compared with the results by analytical and finite element method (FEM) results, respectively.
The extremely local electric field enhancement and light confinement is demonstrated in dielectri... more The extremely local electric field enhancement and light confinement is demonstrated in dielectric waveguide with corner and gap geometry. The numerical results reveal the local electric field enhancement in the vicinity of the apex of fan-shaped waveguide. Classical electromagnetic theory predicts that the field enhancement and confinement abilities increase with decreasing radius of rounded corner (r) and gap (g), and show singularity for infinitesimal r and g. For practical parameters with r = g = 10 nm, the mode area of opposing apex-to-apex fan-shaped waveguides can be as small as 4 × 10 −3 A0 (A0 = λ 2 /4), far beyond the diffraction limit. This way of breaking diffraction limit with no loss outperforms plasmonic waveguides, where light confinement is realized at the cost of huge intrinsic loss in the metal. Furthermore, we propose a structure with dielectric bow-tie antenna on a silicon-on-insulator waveguide, whose field enhancement increases by one order. The lossless dielectric corner and gap structures offer an alternative method to enhance the light-matter interaction without metal nano-structure, and will find applications in quantum electrodynamics, sensors and nano-particle trapping.
ABSTRACT In two-component Bose-Einstein condensates, the one-axis twisting Hamiltonian leads to s... more ABSTRACT In two-component Bose-Einstein condensates, the one-axis twisting Hamiltonian leads to spin squeezing with a limitation that scales with the number of atoms as ${N}^{$-${}2/3}$. We propose a scheme to transform the one-axis twisting Hamiltonian into a two-axis twisting Hamiltonian, resulting in enhanced spin squeezing proportional to ${N}^{$-${}1}$ approaching the Heisenberg limit. Instead of pulse sequences, only one continuous driving field is required to realize such a transformation, thus the scheme is promising for experimental realization of a two-axis twisting Hamiltonian. Quantum information processing and quantum metrology may benefit from this method in the future.
A scheme to achieve spin squeezing using a geometric phase induced by a single mechanical mode is... more A scheme to achieve spin squeezing using a geometric phase induced by a single mechanical mode is proposed. The analytical and numerical results show that the ultimate degree of spin squeezing depends on the parameter n th +1/2 Q √ N , which is the ratio between the thermal excitation, the quality factor and square root of ensemble size. The undesired coupling between the spin ensemble and the bath can be efficiently suppressed by Bang-Bang control pulses. With high quality factor, the ultimate limit of the ideal one-axis twisting spin squeezing can be obtained for an NV ensemble in diamond.
Light is usually confined in photonic structures with a band gap or relatively high refractive in... more Light is usually confined in photonic structures with a band gap or relatively high refractive index for broad scientific and technical applications. Here, a light confinement mechanism is proposed based on the photonic bound state in the continuum (BIC). In a low-refractive-index waveguide on a highrefractive-index thin membrane, optical dissipation is forbidden because of the destructive interference of various leakage channels. The BIC-based low-mode-area waveguide and high-Q microresonator can be used to enhance light-matter interaction for laser, nonlinear optical and quantum optical applications. For example, a polymer structure on a diamond membrane shows excellent optical performance that can be achieved with large fabrication tolerance. It can induce strong coupling between photons and the nitrogen-vacancy center in diamond for scalable quantum information processors and networks.
Science China Physics, Mechanics & Astronomy, 2015
ABSTRACT In an optomechanical resonator, the optical and mechanical excitations can be coherently... more ABSTRACT In an optomechanical resonator, the optical and mechanical excitations can be coherently converted, which induces a transparency window for a weak probe laser beam. Here, we report an experimental study of transient optomechanically induced transparency (OMIT) using the silica microsphere with the breathing modes. The transient OMIT behavior obtained are in good agreement with theoretical calculations. In addition, the coherent interconversion between optical and mechanical excitations that can be used for light storage and readout has also been studied here. Our experimental results indicate that the light storage is closely related to the process of OMIT, and the photon-phonon conversion can be further applied to optical wavelength or optical mode conversion.
A dielectric body couples with electromagnetic fields through radiation pressure and electrostric... more A dielectric body couples with electromagnetic fields through radiation pressure and electrostrictive forces, which mediate phonon-photon coupling in cavity optomechanics. In a magnetic medium, according to the Korteweg-Helmholtz formula, which describes the electromagnetic force density acting on a medium, magneostrictive forces should arise and lead to phonon-magnon interaction. We report such a coupled phonon-magnon system based on ferrimagnetic spheres, which we term as cavity magnomechanics, by analogy to cavity optomechanics. Coherent phonon-magnon interactions, including electromagnetically induced transparency and absorption, are demonstrated. Because of the strong hybridization of magnon and microwave photon modes and their high tunability, our platform exhibits new features including parametric amplification of magnons and phonons, triple-resonant photon-magnon-phonon coupling, and phonon lasing. Our work demonstrates the fundamental principle of cavity magnomechanics and ...
Journal of the American Chemical Society, Jan 5, 2016
Nanoscale lasers are ideal light signal sources for integrated photonic devices. Most of the pres... more Nanoscale lasers are ideal light signal sources for integrated photonic devices. Most of the present lasers made of dielectric materials are restricted to being larger than half the wavelength of the optical field. Plasmon lasers made from metallic nanostructures can help to break the diffraction limit, yet they suffer from low optical pump efficiency and low quality factors. Integrating dielectric lasers with plasmonic waveguides to construct hybrid material systems may circumvent these problems and combine the advantages of both components. Here, we demonstrate the output of dielectric lasers at subwavelength scale via photon-plasmon coupling in rationally designed perovskite/silver heterostructures. The perovskite crystals offer the gain and high-Q cavity for low threshold laser generation while the embedded silver nanowires (AgNWs) help to output the lasing modes efficiently in the form of surface plasmons. The output coupling can be modulated by controlling the resonant modes o...
2012 7th IEEE International Conference on Nano/Micro Engineered and Molecular Systems (NEMS), 2012
Whispering gallery modes" (WGM) optical micro-and nano resonators are important category in nanop... more Whispering gallery modes" (WGM) optical micro-and nano resonators are important category in nanophotonics researches. The ultra-high quality factor (Q) makes them promising ranging from sensors, filters to low threshold sources. In the above supplications, the frequency stability of the WGM is critical, which is determined by several factors. In this paper, using the microsphere resonator we construct a robust packaged microsphere-taper coupling system (MTCS) to stabilize the resonant WGMs. Furthermore, a stable frequency references platform based on the packaged microcavity unit is constructed. This stable frequency references platform can eliminate the noise of the WGM, and promote the microresonator researches.
Extensive efforts have been expended in developing hybrid quantum systems to overcome the short c... more Extensive efforts have been expended in developing hybrid quantum systems to overcome the short coherence time of superconducting circuits by introducing the naturally long-lived spin degree of freedom. Among all the possible materials, single-crystal yttrium iron garnet has shown up recently as a promising candidate for hybrid systems, and various highly coherent interactions, including strong and even ultrastrong coupling, have been demonstrated. One distinct advantage in these systems is that spins form well-defined magnon modes, which allows flexible and precise tuning. Here we demonstrate that by dissipation engineering, a non-Markovian interaction dynamics between the magnon and the microwave cavity photon can be achieved. Such a process enables us to build a magnon gradient memory to store information in the magnon dark modes, which decouple from the microwave cavity and thus preserve a long lifetime. Our findings provide a promising approach for developing long-lifetime, mul...
A transient and high sensitivity sensor based on high-Q microcavity is proposed and studied theor... more A transient and high sensitivity sensor based on high-Q microcavity is proposed and studied theoretically. There are two ways to realize the transient sensor: monitor the spectrum by fast scanning of probe laser frequency or monitor the transmitted light with fixed laser frequency. For both methods, the non-equilibrium response not only tells the ultrafast environment variance, but also enable higher sensitivity. As examples of application, the transient sensor for nanoparticles adhering and passing by the microcavity is studied. It's demonstrated that the transient sensor can sense coupling region, external linear variation together with the speed and the size of a nanoparticle. We believe that our researches will open a door to the fast dynamic sensing by microcavity.
A photonic integrated circuit (PIC) is the optical analogy of an electronic loop in which photons... more A photonic integrated circuit (PIC) is the optical analogy of an electronic loop in which photons are signal carriers with high transport speed and parallel processing capability. Besides the most frequently demonstrated silicon-based circuits, PICs require a variety of materials for light generation, processing, modulation, and detection. With their diversity and flexibility, organic molecular materials provide an alternative platform for photonics; however, the versatile fabrication of organic integrated circuits with the desired photonic performance remains a big challenge. The rapid development of flexible electronics has shown that a solution printing technique has considerable potential for the large-scale fabrication and integration of microsized/nanosized devices. We propose the idea of soft photonics and demonstrate the function-directed fabrication of high-quality organic photonic devices and circuits. We prepared size-tunable and reproducible polymer microring resonators ...
We propose a new approach to realize all-optical circulator based on stimulated Brillouin scatter... more We propose a new approach to realize all-optical circulator based on stimulated Brillouin scattering in an integrated microresonator. Stimulated Brillouin scattering is a basic interaction between photon and traveling acoustic wave resulted from electrostriction and photoelastic effects. Due to the phase-matching requirement, the circulating acoustic wave can only couple to probe light which propagating along or opposite to the pump laser direction, thus exhibits a non-reciprocal phase shift. Combined with Mach-Zehnder interferometer, the optical circulator can be realized. Though the bandwidth is relatively small because of the narrow-band nature of microresonator, this magnetic-free all-optical integrated circulator may be applied for future on-chip photonic information processing.
We develop an architecture for distributed quantum computation using quantum bus of plasmonic cir... more We develop an architecture for distributed quantum computation using quantum bus of plasmonic circuits and spin qubits in self-assembled quantum dots. Deterministic quantum gates between two distant spin qubits can be reached by using an adiabatic approach in which quantum dots couple with highly detuned plasmon modes in a metallic nanowire. Plasmonic quantum bus offers a robust and scalable platform for quantum optics experiments and the development of on-chip quantum networks composed of various quantum nodes, such as quantum dots, molecules and nanoparticles.
The mechanism of unidirectional emission of high Q Whispering Gallery mode in deformed circular m... more The mechanism of unidirectional emission of high Q Whispering Gallery mode in deformed circular micro- cavities is studied and firstly presented in this paper. In phase space, light in the chaotic sea leaks out the cavity through the refraction regions, whose positions are controlled by stable islands. Moreover, the positions of fixed points according to the critical line in unstable manifolds mainly determines the light leak out from which refraction region and the direction of the emission. By controlling the cavity shape, we can tune the leaky regions, as well as the positions of fixed points, to achieve unidirectional emission high Q cavities with narrow angular divergence both in high and low refractive index mater
We propose to use efficient quantum error correcting codes with multilevel systems to protect enc... more We propose to use efficient quantum error correcting codes with multilevel systems to protect encoded quantum information from erasure errors and efficient implementation to repetitively correct these errors. Our scheme makes use of quantum polynomial codes to encode quantum information and generalizes teleportation based error correction for multilevel systems to repetitively correct photon erasures and operation errors. We discuss the application of our scheme for one-way quantum repeaters and discuss their physical implementation using atom mediated multiqubit gates.
In two-component BEC, the one-axis twisting Hamiltonian leads to spin squeezing with the limitati... more In two-component BEC, the one-axis twisting Hamiltonian leads to spin squeezing with the limitation that scales with the number of atoms as $N^{-\frac{2}{3}}$. We propose a scheme to transform the one-axis twisting Hamiltonian into a two-axis twisting Hamiltonian, resulting in enhanced spin squeezing $\propto N^{-1}$ approaching the Heisenberg limit. Instead of pulse sequences, only one continuous driving field is required to realizing such transforming, thus the scheme is promising for experiment realizations, to an one-axis twisting Hamiltonian. Quantum information processing and quantum metrology may benefit from this method in the future.
A new method based on the boundary element method (BEM) is developed to calculate high quality fa... more A new method based on the boundary element method (BEM) is developed to calculate high quality factors of whispering-gallery modes by studying the Poynting vector. The method has high calculation accuracy, which exceeds traditional methods with the same PC computation resource. To demonstrate the feasibility of the present method, circular and quadrupole microcavities are investigated with this method and compared with the results by analytical and finite element method (FEM) results, respectively.
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Papers by Chang-Ling Zou