arXiv subjects

Hailin Wang

Publications and source records attributed to Hailin Wang.

49 records · Page 3Linked to original sources

arXiv2014

Optomechanical Ramsey Interferometry

We adopt the Ramsey's method of separated oscillatory fields to study coherences of the mechanical system in an optomechanical resonator. The high resolution Ramsey fringes are observed in the emission optical field, when two pulses separated in time are applied. We develop a theory to describe the transient optomechanical behavior underlying the Ramsey fringes. We also perform the experimental demonstration using a silica microresonator. The method is versatile and can be adopted to different types of mechanical resonators, electromechanical resonators.

quant-ph↗

arXiv2014

Non-Reciprocal Brillouin Scattering Induced Transparency

Electromagnetically induced transparency (EIT) provides a powerful mechanism for controlling light propagation in a dielectric medium, and for producing slow and fast light. EIT traditionally arises from destructive interference induced by a nonradiative coherence in an atomic system. Stimulated Brillouin scattering (SBS) of light from propagating hypersonic acoustic waves has also been used successfully for the generation of slow and fast light. However, EIT-type processes based on SBS were considered infeasible because of the short coherence lifetime of hypersonic phonons. Here, we report a new Brillouin scattering induced transparency (BSIT) phenomenon generated by acousto-optic interaction of light with long-lived propagating phonons. We demonstrate that BSIT is uniquely non-reciprocal due to the propagating acoustic phonon wave and accompanying momentum conservation requirement. Using a silica microresonator having naturally occurring forward-SBS phase-matched modal configuration, we show that BSIT enables compact and ultralow-power slow-light generation with delay-bandwidth product comparable to state-of-the-art SBS systems.

physics.optics↗

arXiv2013

Optically-driven nuclear-spin-selective Rabi oscillations of single electron spins in diamond

Optically-driven Rabi oscillations of single electron spins in a diamond nitrogen vacancy center are realized with two Raman-resonant optical pulses that are detuned from the respective dipole optical transitions. The Rabi oscillations are nuclear-spin selective and are robust against rapid decoherence of the underlying optical transitions, opening the door to generating phonon-mediated spin entanglement in an optically-driven spin-phonon system. A direct comparison between the Rabi oscillations and simulated Raman adiabatic passage along with a detailed theoretical analysis provide a wealth of information on the coherent spin dynamics and in particular reveal that decoherence and environmental fluctuations associated with the optical transitions affect the fidelity of the Rabi oscillations through relatively large jumps in the transition frequencies.

quant-ph↗

arXiv2013

Generating Robust Optical Entanglement in Weak Coupling Optomechanical Systems

A pulsed scheme for generating robust optical entanglement via the coupling of two optical modes to a mechanical oscillator is proposed. This scheme is inspired by the Sørensen-Mølmer approach for entangling trapped ions in a thermal environment and is based on the use of optical driving pulses that are slightly detuned from the respective sideband resonance. We show that for certain pulse durations, the optomechanical interaction can return the mechanical oscillator to its initial state. The corresponding entanglement generation is robust against thermal mechanical noise in the weak as well as the strong coupling regimes. Significant optical entanglement can be generated in the weak coupling regime, even in the presence of a large thermal phonon occupation.

quant-ph↗

arXiv2013

Nuclear-spin-dependent coherent population trapping of single nitrogen vacancy centers in diamond

Coherent population trapping (CPT) provides a highly sensitive means for probing the energy level structure of an atomic system. For a nitrogen vacancy center in diamond, the CPT offers an alternative to the standard optically-detected magnetic resonance method for measuring the hyperfine structure of the electronic ground states. We show that the nuclear spin dependent CPT measures directly the hyperfine splitting of these states due to the 14N nuclear spin. The CPT spectral response obtained in the presence of a strong microwave field, resonant or nearly resonant with a ground state spin transition, maps out the dynamic Stark splitting induced by the coherent spin excitation.

quant-ph↗

arXiv2013

Optomechanical light storage in a silica microresonator

Coherent inter-conversion between an optical and a mechanical excitation in an optomechanical resonator can be used for the storage of an optical pulse as an excitation in a mechanical oscillator. This optomechanical light storage is enabled by external writing and readout pulses at one mechanical frequency below the optical resonance. In this paper, we expand an earlier experimental study [Phys. Rev. Lett. 107, 133601 (2011)] on storing an optical pulse as a radial breathing mode in a silica microsphere. We show that the heterodyne beating between a readout pulse and the corresponding retrieved pulse features a periodic oscillation with a well-defined phase and with the beating period given by the mechanical frequency, demonstrating directly the coherent nature of the light storage process. The coherent inter-conversion accelerates with increasing optomechanical coupling rates, providing an effective mechanism for tailoring the temporal profile of the retrieved pulse. Experimental studies on both light storage and optomechanically induced transparency under nearly the same conditions also illustrate the connections between these two closely-related processes.

quant-ph↗

arXiv2012

Optical wavelength conversion via optomechanical coupling in a silica resonator

We report the experimental demonstration of converting coherent optical fields between two different optical wavelengths by coupling two optical modes to a mechanical breathing mode in a silica resonator. The experiment is based on an itinerant approach, in which state-mapping from optical to mechanical and from mechanical to another optical state takes place simultaneously. In contrast to conventional nonlinear optical processes, optomechanical impedance matching as well as efficient optical input-output coupling, instead of phase-matching, plays a crucial role in optomechanics-based wavelength conversion.

quant-ph↗

arXiv2011

Storing light as a mechanical excitation in a silica optomechanical resonator

We report the experimental demonstration of optomechanical light storage in a silica resonator. We use writing and readout laser pulses tuned to one mechanical frequency below an optical cavity resonance to control the coupling between the mechanical displacement and the optical field at the cavity resonance. The writing pulse maps a signal pulse at the cavity resonance to a mechanical excitation. The readout pulse later converts the mechanical excitation back to an optical pulse. The light storage lifetime is determined by the relatively long damping time of the mechanical excitation.

quant-ph↗

arXiv2010

Optical wavelength conversion of quantum states with optomechanics

An optomechanical interface that converts quantum states between optical fields with distinct wavelengths is proposed. A mechanical mode couples to two optical modes via radiation pressure and mediates the quantum state mapping between the two optical modes. A sequence of optomechanical $π/2$ pulses enables state-swapping between optical and mechanical states as well as the cooling of the mechanical mode. Theoretical analysis shows that high fidelity conversion can be realized for states with small photon numbers in systems with experimentally achievable parameters. The pulsed conversion process also makes it possible to maintain high conversion fidelity at elevated bath temperatures.

quant-ph↗

arXiv2006

Cavity QED with Diamond Nanocrystals and Silica Microspheres

Normal mode splitting is observed in a cavity QED system, in which nitrogen vacancy centers in diamond nanocrystals are coupled to whispering gallery modes in a silica microsphere. The composite nanocrystal-microsphere system takes advantage of the exceptional spin properties of nitrogen vacancy centers as well as the ultra high quality factor of silica microspheres. The observation of the normal mode splitting indicates that the dipole optical interaction between the relevant nitrogen vacancy center and whispering gallery mode has reached the strong coupling regime of cavity QED.

cond-mat.mes-hall↗

arXiv2004

Inducing electron spin coherence in GaAs quantum well waveguides: Spin coherence without spin precession

Electron spin coherence is induced via light-hole transitions in a quantum well waveguide without either an external or internal DC magnetic field. In the absence of spin precession, the induced spin coherence is detected through effects of quantum interference in the spectral domain coherent nonlinear optical response. We interpret the experimental results qualitatively using a simple few-level model with only the optical transition selection rule as its basic ingredients.

cond-mat.mes-hall↗

arXiv2003

Directional Tunneling Escape from Nearly Spherical Optical Resonators

We report the surprising observation of directional tunneling escape from nearly spherical fused-silica optical resonators, in which most of the phase space is filled with nonchaotic regular trajectories. Experimental and theoretical studies of the dependence of the far-field emission pattern on both the degree of deformation and the excitation condition show that nonperturbative phase-space structures in the internal ray dynamics profoundly affect tunneling leakage of the whispering-gallery modes.

physics.optics↗

arXiv1999

Coupling nanocrystals to a high-$Q$ silica microsphere: entanglement in quantum dots via photon exchange

Coupling nanocrystals (quantum dots) to a high-$Q$ whispering gallery mode (WGM) of a silica microsphere, can produce a strong coherent interaction between the WGM and the electronic states of the dots. Shifting the resonance frequencies of the dots, for instance by placing the entire system in an electric potential, then allows this interaction to be controlled, permitting entangling interactions between different dots. Thus, this system could potentially be used to implement a quantum computer.

quant-ph↗