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Report

Teaser, summary, work performed and final results

Periodic Reporting for period 3 - QLev4G (Quantum control of levitated massive mechanical systems: a new approach for gravitational quantum physics)

Teaser

The main objective of QLev4G is to establish quantum control of levitated massive mechanical systems as an approach for quantum experiments in a hitherto unachievable parameter regime of large mass and long coherence times. The motivation for this program is to enable a new...

Summary

The main objective of QLev4G is to establish quantum control of levitated massive mechanical systems as an approach for quantum experiments in a hitherto unachievable parameter regime of large mass and long coherence times. The motivation for this program is to enable a new class of experiments at the interface between quantum physics and gravity. Interfacing these two major theories, in particular through novel empirical approaches, belongs to one of the outstanding big challenges of modern science and hence society.

Work performed

We have implemented optical trapping, 3d-readout and manipulation of sub-micron dielectric particles inside evacuated hollow-core photonic-crystal fibres (1). This is a first step for deterministic particle delivery (both in position and center-of-mass temperature) via an optical conveyor belt into a high-vacuum environment.

We have studied photonic crystal structures at ultra-low temperatures (< 50mK). This will prove helpful for future optical levitation experiments in cryogenic environments (2).

We have implemented optical trapping of sub-micron dielectric particles in high vacuum (< 1e-7 mbar) using a single-beam optical dipole trap and without the need for additional external feedback. This is an important prerequisite to achieve coupling to an optical cavity in the strong cooperativity regime.

We have performed first proof-of-concept demonstrations of stable magnetic levitation of type-II superconducting micron-scale particles under vacuum conditions (< 1e-6 mbar) and at low temperatures (< 20K). This is a promising step towards establishing magnetic levitation as a platform for extended quantum coherence with massive particles.

We have concluded a full design study for an experiment that is capable of measuring the gravitational force between millimeter scale objects (3). We analyze in detail the technical requirements and the effect of other, non-Newtonian forces. Using conservative parameters we can improve the current limit for sensing the gravitational field of a small source mass by three orders of magnitude, and we highlight potential order of magnitudes improvement for future experiments.

Final results

All results described above go significantly beyond the current state of the art by operating in a parameter regime or under conditions that have previously not been achieved.

Wider implications: Our proof-of-concept demonstration of superconducting levitation has generated a plethora of new ideas for novel on-chip magneto-mechanical sensing platforms. They have formed the nucleus for a new collaborative FET-Open project (MaQSens) that involves leading academic and industrial partners to pursue these ideas further.

Website & more info

More info: http://aspelmeyer.quantum.at.