Focus session ‘Quantum Physics in Space’

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Date 21/11/2018

Time 16:30 – 19:30

Description

In the context of future space-based experiments using macrosopic quantum systems for testing the foundations of quantum physics, this focus session is dedicated to the state of the art in ground-based experiments, potential future experiments and the case for space of those efforts.

Organizers:

Hendrik Ulbricht, Rainer Kaltenbaek
(contact: h.ulbricht_at_soton.co.uk or rainer.kaltenbaek_at_oeaw.ac.at)

Hosts:
R. Kaltenbaek, A. Bassi, M. Paternostro, J. Bateman, H. Ulbricht, U. Johann (MAQRO)
and
O. Jennrich (ESA)

Venue:

ESTEC
Keplerlaan 1
2201 AZ Noordwijk
The Netherlands
the venue is the same as for the 3rd Quantum Technology – Implementations for Space Workshop
you can find directions here

	November 21st
16:30 – 16:45	Opening
16:45 – 17:20	Prof. Peter Barker (UCL): Levitated quantum optomechanics with charged particles
17:20 – 17:55	Prof. Tjerk Oosterkamp (Leiden Univ.): Progress and challenges in demonstrating CSL or quantum superpositions in mechanical resonators
17:55 – 18:25	Break with refreshments
18:25 – 18:50	Prof. Sougato Bose (UCL): Probing the Quantum Coherent Behaviour of Gravity
18:50 – 19:25	Prof. Angelo Bassi (Univ. Trieste): Why quantum physics in space?

Abstracts:

Prof. Peter Barker (UCL): Levitated quantum optomechanics with charged particles

Levitated optomechanics has become an important platform for exploring the macroscopic limits of quantum mechanics. In this talk I will describe the methods we have developed to cool and control the centre-of-mass motion of nanoparticles which are enabling experiments in this new frontier. This includes cavity cooling in a hybrid optical-electrical trap, feedback cooling, and internal cooling of trapped particles using laser refrigeration. I will also discuss trap loading methods and particle stability in these systems, and outline prospects and challenges for future experiments.

Prof. Tjerk Oosterkamp (Leiden Univ.): Progress and challenges in demonstrating CSL or quantum superpositions in mechanical resonators

We give a summary of our recent experiments with mechanical resonators (resonance frequency 2-5 kHz) that we use for magnetic resonance force microscopy . We detect the thermal motion of our mechanical resonators using a SQUID. We discuss the detection sensitivity and its noise, and focus especially on the vibration isolation issues, because at these temperatures external vibrations need to be damped very much in order to see the thermal motion only. We are able to reach thermal equilibrium of our mechanical resonators down to 15 mK and still detect the thermal motion, despite the fact that we work in a cryogen free dilution refrigerator (i.e. pulse tube cooled). Our force noise is approximately 0.5 aN/sqrt(Hz) and our detection sensitivity can be as low as 200 fm/sqrt(Hz), and we have reached 160 microKelvin using cantilever cooling with a starting temperature of 90 mK. We are preparing nuclear demagnetization experiments and have seen a decrease in cantilever damping down to 6 mK and hope to be able to reach temperatures below 1 mK. We discuss how a resonator may be used to demonstrate that it was in a superposition of states and which operation temperature and Q factor of the resonator is needed to do so.

Prof. Sougato Bose (UCL): Probing the Quantum Coherent Behaviour of Gravity

A lack of empirical evidence has lead to a debate on whether gravity is a quantum entity. Motivated by this, we will present a feasible idea for such a test based on the principle that two objects cannot be entangled without a quantum mediator. We will show that despite the weakness of gravity, the phase evolution induced by the gravitational interaction of two micron size test masses in adjacent matter-wave interferometers can detectably entangle them even when they are placed far apart enough to keep Casimir-Polder forces at bay. A prescription for witnessing this entanglement, which certifies gravity as a quantum coherent mediator, is also provided and can be measured through simple spin correlations. As an addendum, and on a rather different topic, we will also describe why matter wave interferometers with mesoscopic masses are also useful in designing compact (meter scale) detectors for low frequency gravitational waves.

Prof. Angelo Bassi (Univ. Trieste): Why testing quantum mechanics in space?

Understanding the limits of validity of quantum theory, in particular of the quantum superposition principle – its building block, is one of the most important tasks of modern physics, not only for its conceptual implications, but also for the impact it can have on future quantum technologies. We will review the state of the art in tests of the quantum superposition principle on earth, and why in order to test quantum theory all the way to the macroscopic world, one eventually has to perform the experiments in space.