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Search Results: 1 - 10 of 17849 matches for " Mark Kasevich "
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Single shot simulations of dynamic quantum many-body systems
Kaspar Sakmann,Mark Kasevich
Physics , 2015,
Abstract: The single-particle density is the most basic quantity that can be calculated from a given many-body wave function. It provides the probability to find a particle at a given position when the average over many realizations of an experiment is taken. However, the outcome of single experimental shots of ultracold atom experiments is determined by the $N$-particle probability density. This difference can lead to surprising results. For example, independent Bose-Einstein condensates (BECs) with definite particle numbers form interference fringes even though no fringes would be expected based on the single-particle density [1-4]. By drawing random deviates from the $N$-particle probability density single experimental shots can be simulated from first principles [1, 3, 5]. However, obtaining expressions for the $N$-particle probability density of realistic time-dependent many-body systems has so far been elusive. Here, we show how single experimental shots of general ultracold bosonic systems can be simulated based on numerical solutions of the many-body Schr\"odinger equation. We show how full counting distributions of observables involving any number of particles can be obtained and how correlation functions of any order can be evaluated. As examples we show the appearance of interference fringes in interacting independent BECs, fluctuations in the collisions of strongly attractive BECs, the appearance of randomly fluctuating vortices in rotating systems and the center of mass fluctuations of attractive BECs in a harmonic trap. The method described is broadly applicable to bosonic many-body systems whose phenomenology is driven by information beyond what is typically available in low-order correlation functions.
Single shot three-dimensional imaging of dilute atomic clouds
Kaspar Sakmann,Mark Kasevich
Physics , 2014, DOI: 10.1364/OL.39.005317
Abstract: Light field microscopy methods together with three dimensional (3D) deconvolution can be used to obtain single shot 3D images of atomic clouds. We demonstrate the method using a test setup which extracts three dimensional images from a fluorescent $^{87}$Rb atomic vapor.
High-order inertial phase shifts for time-domain atom interferometers
Kai Bongs,Romain Launay,Mark A. Kasevich
Physics , 2002,
Abstract: High-order inertial phase shifts are calculated for time-domain atom interferometers. We obtain closed-form analytic expressions for these shifts in accelerometer, gyroscope, optical clock and photon recoil measurement configurations. Our analysis includes Coriolis, centrifugal, gravitational, and gravity gradient-induced forces. We identify new shifts which arise at levels relevant to current and planned experiments.
Atom interferometric gravitational wave detection using heterodyne laser links
Jason M. Hogan,Mark A. Kasevich
Physics , 2015,
Abstract: We propose a scheme based on a heterodyne laser link that allows for long baseline gravitational wave detection using atom interferometry. While the baseline length in previous atom-based proposals is constrained by the need for a reference laser to remain collimated as it propagates between two satellites, here we circumvent this requirement by employing a strong local oscillator laser near each atom ensemble that is phase locked to the reference laser beam. Longer baselines offer a number of potential advantages, including enhanced sensitivity, simplified atom optics, and reduced atomic source flux requirements.
A spatially and temporally localized sub-laser-cycle electron source
Peter Hommelhoff,Catherine Kealhofer,Mark A. Kasevich
Physics , 2006, DOI: 10.1103/PhysRevLett.97.247402
Abstract: We present an experimental and numerical study of electron emission from a sharp tungsten tip triggered by sub-8 femtosecond low power laser pulses. This process is non-linear in the laser electric field, and the non-linearity can be tuned via the DC voltage applied to the tip. Numerical simulations of this system show that electron emission takes place within less than one optical period of the exciting laser pulse, so that an 8 fsec 800 nm laser pulse is capable of producing a single electron pulse of less than 1 fsec duration. Furthermore, we find that the carrier-envelope phase dependence of the emission process is smaller than 0.1% for an 8 fsec pulse but is steeply increasing with decreasing laser pulse duration.
Backaction noise produced via cavity-aided nondemolition measurement of an atomic clock state
Igor Teper,Geert Vrijsen,Jongmin Lee,Mark A. Kasevich
Physics , 2008, DOI: 10.1103/PhysRevA.78.051803
Abstract: We use a quantum nondemolition measurement to probe the collective pseudospin of an atomic ensemble in a high-finesse optical cavity. We analyze the backaction antisqueezing produced by the measurement process to show that our protocol could create conditional spin squeezing in the atomic ensemble.
Light-pulse atom interferometry
Jason M. Hogan,David M. S. Johnson,Mark A. Kasevich
Physics , 2008,
Abstract: The light-pulse atom interferometry method is reviewed. Applications of the method to inertial navigation and tests of the Equivalence Principle are discussed.
Reaching 7Li BEC with a Mini-Trap
Ruquan Wang,Mingchang Liu,Francesco Minardi,Mark Kasevich
Physics , 2006,
Abstract: A novel mm-scale Ioffe-Pritchard trap is used to achieve Bose-Einstein condensation in 7Li. The trap employs free-standing copper coils integrated onto a direct-bond copper surface electrode structure. The trap achieves a radial magnetic gradient of 420 G/cm, an axial oscillation frequency of 50 Hz and a trap depth of 66 G with a 100 A drive current and 7 W total power dissipation.
Ultrafast laser-triggered emission from hafnium carbide tips
Catherine Kealhofer,Seth M. Foreman,Stefan Gerlich,Mark A. Kasevich
Physics , 2011, DOI: 10.1103/PhysRevB.86.035405
Abstract: Electron emission from hafnium carbide (HfC) field emission tips induced by a sub-10 fs, 150 MHz repetition rate Ti:sapphire laser is studied. Two-photon emission is observed at low power with a moderate electric bias field applied to the tips. As the bias field and/or laser power is increased, the average current becomes dominated by thermally-enhanced field emission due to laser heating: both the low thermal conductivity of HfC and the laser's high repetition rate can lead to a temperature rise of several hundred Kelvin at the tip apex. The contribution of current from a thermal transient at times shorter than the electron-phonon coupling time is considered in the context of the two-temperature model. Under the conditions of this experiment, the integrated current from the thermal transient is shown to be negligible in comparison with the two-photon emission. A finite element model of the laser heating and thermal conduction supports these conclusions and is also used to compare the nature of thermal effects in HfC, tungsten, and gold tips.
Testing Atom and Neutron Neutrality with Atom Interferometry
Arvanitaki, Asimina;Dimopoulos, Savas;Geraci, Andrew A.;Hogan, Jason;Kasevich, Mark
High Energy Physics - Phenomenology , 2007, DOI: 10.1103/PhysRevLett.100.120407
Abstract: We propose an atom-interferometry experiment based on the scalar Aharonov-Bohm effect which detects an atom charge at the 10^{-28}e level, and improves the current laboratory limits by 8 orders of magnitude. This setup independently probes neutron charges down to 10^{-28}e, 7 orders of magnitude below current bounds.
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