arXiv subjects

Jay E. Sharping

Publications and source records attributed to Jay E. Sharping.

9 recordsLinked to original sources

arXiv2023

An N-loop potential energy model for levitated mm-scale magnets in cm-scale superconducting coaxial microwave resonators

The levitation of a macroscopic object within a superconducting resonator provides a unique and novel platform to study optomechanics, quantum information, and gravitational wave detection. Existing mirror-method and single-loop models for calculating magnet levitation are insufficient for predicting the position and motion of the levitated magnet. If the cavity-magnet interaction is modeled using a large number of smaller surface current loops, one can quantitatively model the dynamics of the levitation of the magnet within the cavity. The magnet's most-likely position and orientation can be predicted for non-trivial cavity geometries and cavity orientations. Knowing the potential energy landscape within the cavity configuration also provides a means to estimate the resonant mechanical frequencies at which the levitated magnet vibrates, and enables tailoring the cavity design for specific outcomes.

physics.app-ph↗

arXiv2022

Comparative study between three models for the levitation height calculation

Magnetic levitation has been demonstrated and characterized within the coaxial microwave cavity [1,2]. A permanent neodymium magnet is levitated from the edge of the finite-size superconductor [3,4]. One challenge is to develop a better method to calculate levitation height [5]. This paper compares three models, the Mirror method, finite-size superconductor, and two-loop model, for the levitation height calculation. The limitations and advantages of each model are discussed in detail.

cond-mat.supr-con↗

arXiv2022

Magnetic levitation within a microwave cavity: characterization, challenges, and possibilities

The low energy losses in the superconducting magnetic levitation make it attractive for exciting applications in physics. Recently, superconducting magnetic levitation has been realized as novel mechanical transduction for the individual spin qubit in the nitrogen-vacancy center [1]. Furthermore, the Meissner has been proposed for the study of modified gravitational wave detection [2]. Meissner levitation within the microwave cavity could open avenues for the novel cavity optomechanical system, readout for quantum object such as the transmon, and magnon, gravitational wave detection, and magnetomechanics [3]. This work characterized magnetic levitation within a microwave. It also discusses possibilities, challenges, and room temperature and cryogenic experiments of the cavity-magnet system.

quant-ph↗

arXiv2021

Demonstrating levitation within a microwave cavity

Levitated systems are desirable due to reduced clamping losses and reduced thermal contact. These advantageous properties have been exploited in optomechanics to achieve ultra-strong coupling between the mechanical mode and the electromagnetic mode. Such schemes provide an opportunity for the quantum manipulation of a macroscopic system. In this letter, we report the first successful experiments with a levitated millimeter-scale neodymium magnet within a centimeter-scale superconducting aluminum coaxial quarter-wave stub cavity. The magnet levitated near the top of the stub, where the electric field is concentrated, perturbs the electric field distribution allowing for small perturbations in the magnet's position to be detected through shifts in the resonance frequency. Resonance spectra are collected via a vector network analyzer (VNA) between temperatures of 5 K and 50 mK revealing movement of the magnet inside of the cavity. Room temperature measurements and finite element calculations are done to calculate the shift in frequency for various positions of the magnet, and an experimentally measured 100 MHz upshift when transitioning into a superconducting state confirms levitation with remanences up to 140 times stronger than the critical field of the aluminum. We achieve levitation heights of 1 - 1.8 mm. We investigate the dependence of levitation height and levitation temperature on the strength of the magnet and, surprisingly, we observe that the levitation temperature and height both increase with permanent magnet strength. Our work describes a novel macroscopic mechanical system capable of sensing and transducing forces, thus allowing for the coupling of disparate classical and quantum systems.

quant-ph↗

arXiv2020

Casimir spring and dilution in macroscopic cavity optomechanics

The Casimir force was predicted in 1948 as a force arising between macroscopic bodies from the zero-point energy. At finite temperatures it has been shown that a thermal Casimir force exists due to thermal rather than zero-point energy and there are a growing number of experiments that characterise the effect at a range of temperatures and distances. Additionally, in the rapidly evolving field of cavity optomechanics there is an endeavor to manipulate phonons and enhance coherence. We demonstrate a new way to achieve this through the first observation of Casimir spring and dilution in macroscopic optomechanics, by coupling a metallic SiN membrane to a photonic re-entrant cavity. The attraction of the spatially-localised Casimir spring mimics a non-contacting boundary condition giving rise to increased strain and acoustic coherence through dissipation dilution. This work invents a new way to manipulate phonons via thermal photons leading to ``in situ'' reconfigurable mechanical states, to reduce loss mechanisms and to create new types of acoustic non-linearity -- all at room temperature.

physics.app-ph↗

arXiv2008

Telecom-Band Entanglement Generation for Chipscale Quantum Processing

We demonstrate polarization-entanglement for non-degenerate and degenerate photon-pairs generated through Kerr-nonlinearity in a nano-scale silicon-on-insulator(SOI) waveguide. We use a compact counter propagating configuration to create two-photon polarization-entangled state, |H>|H> + |V>|V>. We observe two-photon interference with visibility > 91% and > 80% for non-degenerate and degenerate photon-pairs, respectively. The experimental structure can be implemented on optical chips as an integrated source of entangled photons for future quantum computer and communication applications.

quant-ph↗

arXiv2004

Coherent resonant interactions and slow light with molecules confined in photonic band-gap fibers

We investigate resonant nonlinear optical interactions and demonstrate induced transparency in acetylene molecules in a hollow-core photonic band-gap fiber at 1.5$μ$m. The induced spectral transmission window is used to demonstrate slow-light effects, and we show that the observed broadening of the spectral features is due to collisions of the molecules with the inner walls of the fiber core. Our results illustrate that such fibers can be used to facilitate strong coherent light-matter interactions even when the optical response of the individual molecules is weak.

physics.optics↗

arXiv2004

Optical-fiber source of polarization-entangled photon pairs in the 1550nm telecom band

We present a fiber based source of polarization-entangled photon pairs that is well suited for quantum communication applications in the 1550nm band of standard fiber-optic telecommunications. Polarization entanglement is created by pumping a nonlinear-fiber Sagnac interferometer with two time-delayed orthogonally-polarized pump pulses and subsequently removing the time distinguishability by passing the parametrically scattered signal-idler photon pairs through a piece of birefringent fiber. Coincidence detection of the signal-idler photons yields biphoton interference with visibility greater than 90%, while no interference is observed in direct detection of either the signal or the idler photons. All four Bell states can be prepared with our setup and we demonstrate violations of CHSH form of Bell's inequalities by up to 10 standard deviations of measurement uncertainty.

quant-ph↗

arXiv2001

Soliton Squeezing in a Mach-Zehnder Fiber Interferometer

A new scheme for generating amplitude squeezed light by means of soliton self-phase modulation is experimentally demonstrated. By injecting 180-fs pulses into an equivalent Mach-Zehnder fiber interferometer, a maximum noise reduction of $4.4 \pm 0.3$ dB is obtained ($6.3 \pm 0.6$ dB when corrected for losses). The dependence of noise reduction on the interferometer splitting ratio and fiber length is studied in detail.

quant-ph↗