53 research outputs found
Concept of an ionizing time-domain matter-wave interferometer
We discuss the concept of an all-optical and ionizing matter-wave
interferometer in the time domain. The proposed setup aims at testing the wave
nature of highly massive clusters and molecules, and it will enable new
precision experiments with a broad class of atoms, using the same laser system.
The propagating particles are illuminated by three pulses of a standing
ultraviolet laser beam, which detaches an electron via efficient single
photon-absorption. Optical gratings may have periods as small as 80 nm, leading
to wide diffraction angles for cold atoms and to compact setups even for very
massive clusters. Accounting for the coherent and the incoherent parts of the
particle-light interaction, we show that the combined effect of phase and
amplitude modulation of the matter waves gives rise to a Talbot-Lau-like
interference effect with a characteristic dependence on the pulse delay time.Comment: 25 pages, 5 figure
Macroscopicity of Mechanical Quantum Superposition States
We propose an experimentally accessible, objective measure for the
macroscopicity of superposition states in mechanical quantum systems. Based on
the observable consequences of a minimal, macrorealist extension of quantum
mechanics, it allows one to quantify the degree of macroscopicity achieved in
different experiments.Comment: 11 pages, 2 figures. v2: Corresponds to the published version, except
for a different numbering of the references. The published "Supplemental
Material" is included as an appendi
Master Equation for the Motion of a Polarizable Particle in a Multimode Cavity
We derive a master equation for the motion of a polarizable particle weakly
interacting with one or several strongly pumped cavity modes. We focus here on
massive particles with complex internal structure such as large molecules and
clusters, for which we assume a linear scalar polarizability mediating the
particle-light interaction. The predicted friction and diffusion coefficients
are in good agreement with former semiclassical calculations for atoms and
small molecules in weakly pumped cavities, while the current rigorous quantum
treatment and numerical assessment sheds a light on the feasibility of
experiments that aim at optically manipulating beams of massive molecules with
multimode cavities.Comment: 30 pages, 5 figure
Research campaign: Macroscopic quantum resonators (MAQRO)
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 to test the foundations of physics in macroscopic quantum experiments at the interface with gravity. Developing the necessary technologies, achieving the required sensitivities and providing the necessary isolation of macroscopic quantum systems from their environment will lay the path for developing novel quantum sensors. Earlier studies showed that the proposal is feasible but that several critical challenges remain, and key technologies need to be developed. Recent scientific and technological developments since the original proposal of MAQRO promise the potential for achieving additional science objectives. The proposed research campaign aims to advance the state of the art and to perform the first macroscopic quantum experiments in space. Experiments on the ground, in micro-gravity, and in space will drive the proposed research campaign during the current decade to enable the implementation of MAQRO within the subsequent decade
Atomic “bomb testing”: the Elitzur–Vaidman experiment violates the Leggett–Garg inequality
Macroscopic quantum resonators (MAQRO)
Quantum physics challenges our understanding of the nature of physical
reality and of space-time and suggests the necessity of radical revisions of
their underlying concepts. Experimental tests of quantum phenomena involving
massive macroscopic objects would provide novel insights into these fundamental
questions. Making use of the unique environment provided by space, MAQRO aims
at investigating this largely unexplored realm of macroscopic quantum physics.
MAQRO has originally been proposed as a medium-sized fundamental-science space
mission for the 2010 call of Cosmic Vision. MAQRO unites two experiments:
DECIDE (DECoherence In Double-Slit Experiments) and CASE (Comparative
Acceleration Sensing Experiment). The main scientific objective of MAQRO, which
is addressed by the experiment DECIDE, is to test the predictions of quantum
theory for quantum superpositions of macroscopic objects containing more than
10e8 atoms. Under these conditions, deviations due to various suggested
alternative models to quantum theory would become visible. These models have
been suggested to harmonize the paradoxical quantum phenomena both with the
classical macroscopic world and with our notion of Minkowski space-time. The
second scientific objective of MAQRO, which is addressed by the experiment
CASE, is to demonstrate the performance of a novel type of inertial sensor
based on optically trapped microspheres. CASE is a technology demonstrator that
shows how the modular design of DECIDE allows to easily incorporate it with
other missions that have compatible requirements in terms of spacecraft and
orbit. CASE can, at the same time, serve as a test bench for the weak
equivalence principle, i.e., the universality of free fall with test-masses
differing in their mass by 7 orders of magnitude.Comment: Proposal for a medium-sized space mission, 28 pages, 9 figures - in
v2, we corrected some minor mistakes and replaced fig. 9 with a
higher-resolution version; Experimental Astronomy, March 2012, Online, Open
Acces
Atomic “bomb testing”: the Elitzur–Vaidman experiment violates the Leggett–Garg inequality
Elitzur and Vaidman have proposed a measurement scheme that, based on the quantum superposition principle, allows one to detect the presence of an object—in a dramatic scenario, a bomb—without interacting with it. It was pointed out by Ghirardi that this interaction-free measurement scheme can be put in direct relation with falsification tests of the macro-realistic worldview. Here we have implemented the “bomb test” with a single atom trapped in a spin-dependent optical lattice to show explicitly a violation of the Leggett–Garg inequality—a quantitative criterion fulfilled by macro-realistic physical theories. To perform interaction-free measurements, we have implemented a novel measurement method that correlates spin and position of the atom. This method, which quantum mechanically entangles spin and position, finds general application for spin measurements, thereby avoiding the shortcomings inherent in the widely used push-out technique. Allowing decoherence to dominate the evolution of our system causes a transition from quantum to classical behavior in fulfillment of the Leggett–Garg inequality
Maxwell's lesser demon: A Quantum Engine Driven by Pointer Measurements
We discuss a self-contained spin-boson model for a measurement-driven engine, in which a demongenerates work from random thermal excitations of a quantum spin via measurement and feedbackcontrol. Instead of granting it full direct access to the spin state and to Landauer’s erasure strokes foroptimal performance, we restrict this lesser demon’s action to pointer measurements, i.e. random orcontinuous interrogations of a damped mechanical oscillator that assumes macroscopically distinctpositions depending on the spin state. The engine could reach simultaneously high output powersand efficiencies and can operate in temperature regimes where quantum Otto engines would fail
Testing spontaneous localization theories with matter-wave interferometry
We propose to test the theory of continuous spontaneous localization (CSL) in an all-optical time-domain Talbot-Lau interferometer for clusters with masses exceeding 10(6) amu. By assessing the relevant environmental decoherence mechanisms, as well as the growing size of the particles relative to the grating fringes, we argue that it will be feasible to test the quantum superposition principle in a mass range excluded by recent estimates of the CSL effect
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