EPJ Quantum Technol. (2016) 3: 5
https://doi.org/10.1140/epjqt/s40507-016-0043-7

Review

Macroscopic Quantum Resonators (MAQRO): 2015 update

¹ Vienna Center for Quantum Science and Technology, University of Vienna, Boltzmanngasse 5, Vienna, Austria
² Department of Physics and Astronomy, University College London, Gower Street, London, UK
³ Department of Physics, University of Trieste, Strada Costiera, 11, Trieste, Italy
⁴ INFN - Trieste Section, Via Valerio, 2, Trieste, Italy
⁵ Department of Physics, College of Science, University of Swansea, Singleton Park, Swansea, UK
⁶ School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham, UK
⁷ Center of Applied Space Technology and Micro Gravity (ZARM), University of Bremen, Am Fallturm, Bremen, Germany
⁸ German Aerospace Center (DLR), Institute of Space Systems, Robert Hooke-Straße 7, Bremen, Germany
⁹ Institute of Quantum Optics and Quantum Information (IQOQI), Austrian Academy of Sciences, Boltzmanngasse 3, Vienna, Austria
¹⁰ ONERA, The French Aerospace Lab, 29 Avenue de la Division Leclerc, Châtillon, France
¹¹ Airbus Defence and Space GmbH, Claude-Dornier-Straße, Immenstaad, Germany
¹² Laboratoire Kastler Brossel, UPMC-Sorbonne Universités, CNRS, Collège de France, ENS-PSL Research University, 4 place Jussieu, Paris, France
¹³ Laboratori Nazionali di Frascati dell’INFN, Via Enrico Fermi, 40, Frascati, Italy
¹⁴ School of Physics and Astronomy, University of St. Andrews, North Haugh, St. Andrews, UK
¹⁵ Wigner Research Center for Physics, P.O. Box 49, Budapest, 1525, Hungary
¹⁶ Institut für Physik, Humboldt-Universität zu Berlin, Newtonstraße 15, Berlin, Germany
¹⁷ Institut für Quantenoptik, Leibniz Universität Hannover, Welfengarten 1, Hannover, Germany
¹⁸ Photonics Laboratory, ETH Zürich, Hönggerbergring 64, Zürich, Switzerland
¹⁹ European Southern Observatory (ESO), Karl-Schwarzschild-Straße 2, Garching bei München, Germany
²⁰ Nordita, KTH Royal Institute of Technology and Stockholm University, Roslagstullsbacken 23, Stockholm, Sweden
²¹ QOLS, Blackett Laboratory, Imperial College London, South Kensington Campus, London, UK
²² ARC Centre for Engineered Quantum Systems, University of Queensland, St. Lucia, Brisbane, Australia
²³ Department of Physics, University of California, 366 LeConte Hall, Berkeley, CA, USA
²⁴ Centre for Theoretical Atomic, Molecular and Optical Physics, School of Mathematics and Physics, Queen’s University, University Road, Belfast, UK
²⁵ ITAMP, Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA, USA
²⁶ EN-STI-TCD, CERN - European Organization for Nuclear Research, Geneva, 23, Switzerland
²⁷ Perimeter Institute for Theoretical Physics, 31 Caroline Street North, Waterloo, ON, Canada
²⁸ Institut für Quantenphysik, Universität Ulm, Albert-Einstein-Allee 11, Ulm, Germany
²⁹ Texas A & M University Institute for Advanced Study (TIAS), Institute for Quantum Science and Engineering (IQSE), and Department of Physics and Astronomy, Texas A & M University, College Station, TX, USA
³⁰ Vienna Center for Quantum Science and Technology, Institute of Atomic and Subatomic Physics, Vienna University of Technology, Stadionallee 2, Vienna, Austria
³¹ Applied Physics, California Institute of Technology, 1200 E California Blvd., Pasadena, CA, USA
³² Institut für Luft- und Raumfahrttechnik, Technische Universität Dresden, Marschnerstraße 32, Dresden, Germany
³³ Dipartimento di Fisica e Astronomia and LENS, INFN, Universitá di Firenze, via G. Sansone, 1, Sesto Fiorentino, Firenze, Italy
³⁴ Physics and Astronomy, University of Southampton, Highfield Campus, Southampton, UK
³⁵ Atomic and Laser Physics, Clarendon Laboratory, University of Oxford, Parks Road, Oxford, UK
³⁶ Center for Quantum Technologies, National University of Singapore, 3 Science Drive 2, Singapore, Singapore

^* e-mail: rainer.kaltenbaek@univie.ac.at

Received: 6 October 2015
Accepted: 6 March 2016
Published online: 24 March 2016

Abstract

Do the laws of quantum physics still hold for macroscopic objects - this is at the heart of Schrödinger’s cat paradox - or do gravitation or yet unknown effects set a limit for massive particles? What is the fundamental relation between quantum physics and gravity? Ground-based experiments addressing these questions may soon face limitations due to limited free-fall times and the quality of vacuum and microgravity. The proposed mission Macroscopic Quantum Resonators (MAQRO) may overcome these limitations and allow addressing such fundamental questions. MAQRO harnesses recent developments in quantum optomechanics, high-mass matter-wave interferometry as well as state-of-the-art space technology to push macroscopic quantum experiments towards their ultimate performance limits and to open new horizons for applying quantum technology in space. The main scientific goal is to probe the vastly unexplored ‘quantum-classical’ transition for increasingly massive objects, testing the predictions of quantum theory for objects in a size and mass regime unachievable in ground-based experiments. The hardware will largely be based on available space technology. Here, we present the MAQRO proposal submitted in response to the 4th Cosmic Vision call for a medium-sized mission (M4) in 2014 of the European Space Agency (ESA) with a possible launch in 2025, and we review the progress with respect to the original MAQRO proposal for the 3rd Cosmic Vision call for a medium-sized mission (M3) in 2010. In particular, the updated proposal overcomes several critical issues of the original proposal by relying on established experimental techniques from high-mass matter-wave interferometry and by introducing novel ideas for particle loading and manipulation. Moreover, the mission design was improved to better fulfill the stringent environmental requirements for macroscopic quantum experiments.