Nonreciprocal Single Photon Frequency Conversion via Chiral Coupling between a V-Type System and a Pair of Waveguides

The single photon frequency conversion is investigated theoretically in the system composed of a V-type system chiral coupling to a pair of waveguides. The single photon scattering amplitudes are obtained using the real-space Hamiltonian. The calculated results show that the probability of single photon frequency down-or up-conversion can reach a unit by choosing appropriate parameters in the non-dissipative system with perfect chiral coupling.We present a nonreciprocal single photon beam splitter whose frequency of the output photon is different from that of the input photon. The influences of dissipations and non-perfect chiral coupling on the single frequency conversion are also shown. Our results may be useful in designing quantum devices at the single-photon level.

A Novel Chiral Cd-organic Network Based on Flexible Coupled Cinnamic Acid

A new metal-organic network, [Cd（CH_3OH）_2（epa）]_n（1）, was synthesized from an achiral coupled cinnamic acid, 3,3？-（（ethane-1,2-diylbis（oxy））bis（2,1-phenylene））diacrylic acid（H_2epa）, and Cd（NO3）2·4H2O under solvothermal conditions. The complex crystallizes in orthorhombic, space group P2_12_12 with a = 9.8286（8）, b = 21.0004（16）, c = 5.5169（4） A, V = 1138.71（15） A3, M_r = 528.81, D_c = 1.542 Mg/cm3, F（000） = 536, Z = 2, the final R = 0.0345 and wR = 0.1101 for 2006 observed reflections（I 〉 2σ（I））. In 1 the epa^（2＋） anions alternately bridge the Cd（II） cations to form a one-dimensional（1D） infinite homochiral helical chain of [Cd（epa）]n. The chiral homohelical chains via hydrogen bonds formed a two-dimensional（2D） network. The photoluminescence of 1 was also investigated in solid state at ambient temperature.

Quantum routing of few photons using a nonlinear cavity coupled to two chiral waveguides

We investigate few-photon scattering properties in two one-dimensional waveguides chirally coupled to a nonlinear cavity.The quantum states of scattered few photons are solved analytically via a real-space approach,and the solution indicates the few-photon reflection and transmission properties.When inputting two photons of equal energy to resonate with the cavity,the propagation characteristics of the two photons will be interesting,which is different from the previous anti-bunching effects with a quantum emitter.More importantly,when the total energy of the two incident photons equals the energy of a nonlinear cavity accommodating two photons,influence of the bound state will become larger to result in disappearance of antibunching effect.However,the bound state has no effect on probability of routing to another waveguide.

Chiral edge state coupling theory of transport in quantum anomalous Hall insulators

The quantum anomalous Hall effect is characterized by a quantized Hall resistance with a vanishing longitudinal resistance.Many experiments reported the quantization of the Hall resistance,which is always accompanied by a non-vanishing longitudinal resistance that is several k?.Meanwhile,the non-vanishing longitudinal resistance exhibits a universal exponential decay with the increase in magnetic field.We propose that the coupling of chiral edge states,which has not been properly evaluated in the previous theories,can give rise to the non-vanishing longitudinal resistance.The coupling between the chiral edges states along the opposite boundaries can be assisted by magnetic domains or defects inside the sample bulk,which has been already identified in recent experiments.Our theory provides a potential mechanism to understand the experimental result in both magnetic topological insulator and moirésuperlattice systems.