A5031134370- Mechanical and Optical Resonators
- Cold Atom Physics and Bose-Einstein Condensates
- Quantum Information and Cryptography
- Quantum Mechanics and Applications
- Orbital Angular Momentum in Optics
- Quantum Electrodynamics and Casimir Effect
- Quantum optics and atomic interactions
- Experimental and Theoretical Physics Studies
- Force Microscopy Techniques and Applications
- Advanced Fiber Laser Technologies
- Advanced MEMS and NEMS Technologies
- Photonic and Optical Devices
- Laser-Matter Interactions and Applications
- Functional Brain Connectivity Studies
- Dementia and Cognitive Impairment Research
- Advanced Frequency and Time Standards
- Atomic and Subatomic Physics Research
- Advanced Thermodynamics and Statistical Mechanics
- Liquid Crystal Research Advancements
- Photonic Crystal and Fiber Optics
- Photorefractive and Nonlinear Optics
- Alzheimer's disease research and treatments
- Electronic and Structural Properties of Oxides
- Single-cell and spatial transcriptomics
- Nanofluid Flow and Heat Transfer
Swansea University
2016-2025
University of Southampton
2006-2017
We demonstrate a simple and robust geometry for optical trapping in vacuum of single nanoparticle based on parabolic mirror the gradient force, we rapid parametric feedback cooling all three motional degrees freedom from room temperature to few mK. A laser at 1550nm, photodiode, are used trapping, position detection, dimensions. Particles with diameters 26nm 160nm trapped without 10$^{-5}$mbar engaged pressure is reduced 10$^{-6}$mbar. Modifications harmonic motion presence noise studied, an...
We propose an interferometric scheme based on untrapped nano-object subjected to gravity. The motion of the center mass (c.m.) free object is coupled its internal spin system magnetically, and a flight developed coherent control. wave packet test object, under spin-dependent force, may then be delocalized macroscopic scale. A gravity induced dynamical phase (accrued solely state, measured through Ramsey scheme) used reveal above spatially superposition spin-nano-object composite that arises...
Do the laws of quantum physics still hold for macroscopic objects - this is at heart Schrödinger's cat paradox or do gravitation yet unknown effects set a limit massive particles? What fundamental relation between and gravity? Ground-based experiments addressing these questions may soon face limitations due to limited free-fall times quality vacuum microgravity. The proposed mission Macroscopic Quantum Resonators (MAQRO) overcome allow such questions. MAQRO harnesses recent developments in...
We experimentally squeeze the thermal motional state of an optically levitated nanosphere by fast switching between two trapping frequencies. The measured phase-space distribution center mass our particle shows typical shape a squeezed state, from which we infer up to 2.7 dB squeezing along one direction. In these experiments average occupancy is high and, even after squeezing, remains in remit classical statistical mechanics. Nevertheless, argue that manipulation scheme described here could...
Atom interferometric sensors and quantum information processors must maintain coherence while the evolving wavefunction is split, transformed recombined, but suffer from experimental inhomogeneities uncertainties in speeds paths of these operations. Several error-correction techniques have been proposed to isolate variable interest. Here we apply composite pulse methods velocity-sensitive Raman state manipulation a freely-expanding thermal atom cloud. We compare several established...
The Schr\"odinger-Newton equation has been proposed as an experimentally testable alternative to quantum gravity, accessible at low energies. It contains self-gravitational terms, which slightly modify the dynamics. Here we show that it distorts spectrum of a harmonic system. Based on this effect, propose optomechanical experiment with trapped microdisc test equation, and can be realized existing technology.
Abstract Dark Matter (DM) is an elusive form of matter which has been postulated to explain astronomical observations through its gravitational effects on stars and galaxies, lensing light around these imprint the Cosmic Microwave Background (CMB). This indirect evidence implies that DM accounts for as much 84.5% all in our Universe, yet it so far evaded attempts at direct detection, leaving such confirmation consequent discovery nature one biggest challenges modern physics. Here we present...
We show theoretically that the noise due to laser induced backaction acting on a small nanosphere levitated in standing-wave trap can be considerably reduced by utilizing suitable reflective boundary. examine spherical mirror geometry as case study of this suppression effect, discussing theoretical and experimental constraints. effects recoil directly, analyzing optical force fluctuations dipolar particle trapped at center mirror. also compute corresponding measurement imprecision an...
We report a compact, stable, gain-switched-diode-seeded master oscillator power amplifier (MOPA), employing direct amplification via conventional Yb(3+)-doped fibers, to generate picosecond pulses with energy of 17.7 μJ and 97-W average output (excluding amplified spontaneous emission) at 5.47-MHz repetition frequency in diffraction-limited single-polarization beam. A maximum peak 197 kW is demonstrated. Such high-energy, high-power, MHz, MOPA great interest for high-throughput material...
Abstract The objective of the proposed macroscopic quantum resonators (MAQRO) mission is to harness space for achieving long free-fall times, extreme vacuum, nano-gravity, and cryogenic temperatures test foundations physics in experiments at interface with gravity. Developing necessary technologies, required sensitivities providing isolation systems from their environment will lay path developing novel sensors. Earlier studies showed that proposal feasible but several critical challenges...
We explore the information which proposed matterwave interferometry experiments with large test masses can provide about parameterizable extensions to quantum mechanics, such as have been explain apparent classical transition. Specifically, we consider a near-field Talbot interferometer and Continuous Spontaneous Localization (CSL). Using Bayesian inference compute effect of decoherence mechanisms including pressure blackbody radiation, find estimates for number measurements required,...
Abstract The Schrödinger–Newton equation has gained attention in the recent past as a nonlinear modification of Schrödinger due to gravitational self-interaction. Such is expected from fundamentally semi-classical theory gravity and can, therefore, be considered test case for necessity quantisation field. Here we provide thorough study effects micron-sized sphere trapped harmonic oscillator potential. We discuss both effect on energy eigenstates dynamical behaviour squeezed states, covering...
Atom interferometers require atom mirrors and beam splitters that can maintain high fidelity even when experimental parameters vary from the ideal. We address use of chirped laser pulses to provide such elements via rapid adiabatic passage, present a prescription for practical offer controlled adiabaticity throughout. Full- half-adiabatic pulses, providing splitters, respectively, are derived, latter examined robustness suitability implementations.
We consider the stimulated Raman transition between two long-lived states via multiple intermediate states, such as hyperfine ground in alkali-metal atoms. present a concise treatment of general, multilevel, off-resonant case, and we show how lightshift emerges naturally this approach. illustrate our results by application to atoms make specific reference cesium. comment on some artifacts, due solely geometrical overlap which are relevant existing experiments.
We report the 1D cooling of ^{85}Rb atoms using a velocity-dependent optical force based upon Ramsey matter-wave interferometry. Using stimulated Raman transitions between ground hyperfine states, 12 cycles interferometer sequence cool freely moving atom cloud from 21 to 3 μK. This pulsed analog continuous-wave Doppler is effective at temperatures down recoil limit; with augmentation pulses increase area, it should more quickly than conventional methods and be suitable for species that lack...
Optical levitation of nanoscale particles has emerged as a platform for precision measurement. Extremely low damping, together with optical interferometric position detection, makes possible exquisite force measurement and promises low-energy tests fundamental physics. Essential to such is an understanding the confidence which parameters can be inferred from spectra estimated indirect provided by interferometry. We present apparatus optimized sensitivity along one motional degree freedom,...
We have demonstrated stabilization of a fiber-optic Mach-Zehnder interferometer, with centimeter-scale path difference, to the transmission minimum for carrier wave frequency-modulated laser beam. A time-averaged extinction 32 dB, limited by bandwidth feedback, was maintained over several hours. The interferometer used remove from 780 nm beam that had been phase modulated at 2.7 GHz.
We demonstrate a simple and robust technique for removal of the carrier wave from phase-modulated laser beam, using non-interferometric method that is insensitive to modulation frequency instead exploits polarization-dependence electro-optic modulation. An actively stabilized system feedback via liquid crystal cell yields long-term suppression in excess 28 dB at expense 6.5 reduction sideband power.
We consider the matterwave interferometric measurement of atomic velocities, which forms a building block for all inertial measurements. A theoretical analysis, addressing both laboratory and frames accounting residual Doppler sensitivity in beamsplitter recombiner pulses, is followed by an experimental demonstration, with measurements velocity distribution within 20 μK cloud rubidium atoms. Our experiments use Raman transitions between long-lived ground hyperfine states, allow quadrature...
The voltage transfer function is a rapid and visually effective method to determine the electrical response of liquid crystal (LC) systems using optical measurements. This relies on crosspolarized intensity measurements as frequency amplitude applied device. Coupled with mathematical model device it can be used time constants properties. We validate photorefractive LC cells main dropped across layers simple nonlinear filter model.
We explore the transfer of an incident light pattern onto liquid crystal (LC) bulk in a photorefractive cell through integrated photoconducting layer that modulates electric field applied to device. The electrical properties and strength modulation are investigated as function intensity well frequency amplitude voltage, for two LCs with very different conductivity. A simplified model is proposed, demonstrating LC conductivity key factor determining beam-coupling strength.
We describe a dynamic magneto-optical trap (MOT) suitable for the use with vacuum systems in which optical access is limited to single window. This technique facilitates long-standing desire of producing integrated atom chips, many are likely have severely restricted compared conventional chambers. 'switching-MOT' relies on synchronized pulsing and magnetic fields at audio frequencies. The trap's beam geometry obtained using planar mirror surface, does not require patterned substrate or...