A5045698402- Quantum Information and Cryptography
- Photonic and Optical Devices
- Quantum Mechanics and Applications
- Quantum optics and atomic interactions
- Quantum Computing Algorithms and Architecture
- Advanced Fiber Laser Technologies
- Mechanical and Optical Resonators
- Neural Networks and Reservoir Computing
- Cold Atom Physics and Bose-Einstein Condensates
- Optical Network Technologies
- Laser-Matter Interactions and Applications
- Atomic and Subatomic Physics Research
- Advanced Fluorescence Microscopy Techniques
- Spectroscopy and Quantum Chemical Studies
- Photorefractive and Nonlinear Optics
- Photonic Crystals and Applications
- Molecular Junctions and Nanostructures
- Advanced Thermodynamics and Statistical Mechanics
- 2D Materials and Applications
- Quantum and electron transport phenomena
- Model Reduction and Neural Networks
- Advanced biosensing and bioanalysis techniques
- Spectroscopy and Laser Applications
- Near-Field Optical Microscopy
- Advanced Frequency and Time Standards
Stanford University
2016-2025
The University of Tokyo
2020
NTT (United States)
2020
Stanford Health Care
2015-2017
Hewlett-Packard (United States)
2014
California Institute of Technology
1999-2008
Physical Measurement Laboratory
2008
Dynamic Systems (United States)
2004
Osaka Prefecture University
2002
Princeton University
1993-2000
We propose a scheme to utilize photons for ideal quantum transmission between atoms located at spatially separated nodes of network. The protocol employs special laser pulses that excite an atom inside optical cavity the sending node so its state is mapped into time-symmetric photon wave packet will enter receiving and be absorbed by there with unit probability. Implementation our would enable reliable transfer or sharing entanglement among distant atoms.
Measurements of the birefringence a single atom strongly coupled to high-finesse optical resonator are reported, with nonlinear phase shifts observed for an intracavity photon number much less than one. A proposal utilize measured conditional implementing quantum logic via quantum-phase gate (QPG) is considered. Within context simple model field transformation, parameters "truth table" QPG determined.
Modern cavity quantum electrodynamics (cavity QED) illuminates the most fundamental aspects of coherence and decoherence in mechanics. Experiments on atoms cavities can be described by elementary models but reveal intriguing subtleties interplay coherent dynamics with external couplings. Recent activity this area has pioneered powerful new approaches to study fueled growth information science. In years come, purview QED will continue grow as researchers build a rich infrastructure attack...
Unconventional, special-purpose machines may aid in accelerating the solution of some hardest problems computing, such as large-scale combinatorial optimizations, by exploiting different operating mechanisms than those standard digital computers. We present a scalable optical processor with electronic feedback that can be realized at large scale room-temperature technology. Our prototype machine is able to find exact solutions of, or sample good approximate to, variety hard instances Ising...
Measurements of the quality factor Q?8×109 are reported for whispering-gallery modes (WGM's) quartz microspheres wavelengths 670, 780, and 850??nm; these results correspond to finesse F?2.2×106.?The observed independence Q from wavelength indicates that losses WGM's dominated by a mechanism other than bulk absorption in fused silica near infrared. Data obtained atomic force microscopy combined with simple model surface scattering suggest can be limited residual inhomogeneities. Absorption...
Benchmarking the coherent Ising machine and D-Wave quantum annealer sheds light on importance of connectivity.
We introduce and discuss the problem of quantum feedback control in context established formulations classical theory, examining conceptual analogies essential differences. describe application state-observer based laws, familiar to systems apply our methods particular case switching state a particle double-well potential.
Feedback control of quantum mechanical systems must take into account the probabilistic nature measurement. We formulate feedback as a problem stochastic nonlinear by considering separately filtering and state for filter. explore use Lyapunov techniques design controllers spin demonstrate possibility stabilizing one outcome measurement with unit probability.
We discuss the optimization of optical microcavity designs based on two-dimensional photonic crystals for purpose strong coupling between cavity field and a single neutral atom trapped within hole. present numerical predictions quality factors mode volumes localized defect modes as function geometric parameters, some experimental challenges related to gas-phase atoms.
We present an experimental demonstration of the power feedbackin quantum metrology, confirming predicted [H. M. Wiseman, Phys. Rev. Lett. 75, 4587 (1995)] superior performanceof adaptive homodyne technique for single-shotmeasurement optical phase. For measurements performed on weak coherentstates with no prior knowledge signal phase, homodyneestimation approaches closer to intrinsic uncertaintythan any previous technique. Our results underscore importanceof real-time feedback reaching limits...
Real-time feedback performed during a quantum nondemolition measurement of atomic spin-angular momentum allowed us to influence the statistics outcome. We showed that it is possible harness backaction as form actuation in control, and thus we describe valuable tool for information science. Our feedback-mediated procedure generates spin-squeezing, which reduction uncertainty resulting entanglement are not conditioned on
We express the quality factor of a mode in terms Fourier transforms its field components and prove that reduction radiation loss can be achieved by suppressing mode's wavevector within light cone. Although this is intuitively clear, our analytical proof gives us insight into how to achieve Q optimization, without delocalization. focus on dipole defect free-standing membranes > 10/sup 4/, while preserving volume order one half cubic wavelength material. The derived expressions conclusions...
I present an experimental realization of a coherent-feedback control system that was recently proposed for testing basic principles linear quantum stochastic theory [M. R. James, H. I. Nurdin, and Petersen, e-print arXiv:quant-ph/0703150v2, IEEE Transactions on Automatic Control (to be published)]. For dynamical plant consisting optical ring resonator, demonstrate $\ensuremath{\sim}7\phantom{\rule{0.3em}{0ex}}\mathrm{dB}$ broadband disturbance rejection injected laser signals via all-optical...
Analyzing the properties of entanglement in many-particle spin-1/2 systems is generally difficult because system's Hilbert space grows exponentially with number constituent particles, N. Fortunately, it still possible to investigate a when state system possesses sufficient symmetry. In this paper, we present practical method for efficiently computing various bipartite measures states symmetric subspace and perform these calculations $N\ensuremath{\sim}{10}^{3}.$ By considering all splits,...
We propose an approach to quantum error correction based on coding and continuous syndrome readout via scattering of coherent probe fields, in which the usual steps measurement discrete restoration are replaced by direct physical processing beams feedback register qubits. Our is well matched implementations that feature solid-state qubits embedded planar electromagnetic circuits, providing autonomous "on-chip" memory design requiring no external clocking or control logic.
We model the cooling of open optical and optomechanical resonators via feedback in linear quadratic Gaussian setting stochastic control theory. show that coherent schemes, which resonator is embedded an interferometer to achieve all-optical feedback, can outperform best possible measurement-based schemes quantum regime low steady-state excitation number. Such performance gains are attributed controller's ability process noncommuting output field quadratures simultaneously without loss...
Realization of a room-temperature ultra-fast photon-number-resolving (PNR) quantum nondemolition (QND) measurement would have significant implications for photonic information processing (QIP), enabling, e.g., deterministic computation in discrete-variable architectures, but the requirement strong coupling has hampered development scalable implementations. In this work, we propose and analyze nonlinear-optical route to PNR QND using quadratic (i.e., $\chi^{(2)}$) nonlinear interactions. We...
The enhanced coupling between atoms and photons inside a high-finesse optical cavity provides novel basis for measurements that continuously monitor atomic degrees of freedom. We describe an experiment in which quantum-electrodynamic effects are utilized real-time detection individual falling through after being dropped from magneto-optical trap. Our technique permits experiments triggered by the presence single optimally coupled atom within mode volume.
Abstract We describe in this article some key themes that emerged during a Caltech/AFOSR Workshop on ‘Principles and Applications of Control Quantum Systems’ (PRACQSYS), held 21–24 August 2004 at the California Institute Technology. This workshop brought together engineers, physicists applied mathematicians to construct an overview new challenges arise when applying constitutive methods control theory nanoscale systems whose behaviour is manifestly quantum. Its primary conclusions were...
We characterize the long-time projective behavior of stochastic master equation describing a continuous, collective spin measurement an atomic ensemble both analytically and numerically. By adding state-based feedback, we show that it is possible to prepare highly entangled Dicke states deterministically.
The shot-noise detection limit in current high-precision magnetometry [Nature (London) 422, 596 (2003)] is a manifestation of quantum fluctuations that scale as 1/sqrt[N] an ensemble N atoms. Here, we develop procedure combines continuous measurement and Kalman filtering [Rep. Math. Phys. 43, 405 (1999)]] to surpass this conventional by exploiting conditional spin squeezing achieve 1/N field sensitivity. Our analysis demonstrates the importance optimal estimation for high bandwidth precision...
Micron scale silicon nitride (SiNx) microdisk optical resonators are demonstrated with Q=3.6×106 and an effective mode volume of 15(λ∕n)3 at near-visible wavelengths. A hydrofluoric acid wet etch provides sensitive tuning the resonances, robust mounting a fiber taper efficient optic coupling to microdisks while allowing unfettered access for laser cooling trapping atoms. Measurements indicate that cesium adsorption on SiNx surfaces significantly red detunes resonances. Parallel integration...
The external fields of optical whispering gallery modes may be used to confine atoms in stable orbits around a dielectric microsphere. As an example, toroidal dipole-force trap (atom gallery) for three-level is investigated, and the possibility achieving atomic (matter–wave) resonator discussed. extremely small electromagnetic mode volumes high Q's should permit circulating photon repeatedly absorbed reemitted by trapped atom.
Single molecule studies have expanded rapidly over the past decade and ability to provide an unprecedented level of understanding biological systems. A common challenge upon introduction novel, data-rich approaches is management, processing, analysis complex data sets that are generated. We a standardized approach for analyzing these in freely available software package SMART: Molecule Analysis Research Tool. SMART provides format organizing easily accessing single data, general hidden...