Elsevier

Acta Astronautica

Volume 63, Issues 1–4, July–August 2008, Pages 165-178
Acta Astronautica

Quantum communications at ESA: Towards a space experiment on the ISS

https://doi.org/10.1016/j.actaastro.2007.12.039Get rights and content

Abstract

The European Space Agency (ESA) has supported since 2002—in the frame of its General Studies Programme—several studies in the field of quantum communications for space systems. As a result of these studies, a European research consortium led by Prof. Zeilinger (Vienna University) submitted the mission proposal Space-QUEST (“QUantum Entanglement for Space ExperimenTs”) to the European Life and Physical Sciences in Space Programme of ESA, aiming at a quantum communications space-to-ground experiment from the International Space Station (ISS). This paper will present the achievements of the ESA studies on quantum communications and discuss the programmatic roadmap and the proposed technology development activities for the implementation of the proposed Space-QUEST experiment on-board the ISS.

Introduction

The emergence of applications and technologies based on the foundations of quantum physics has revolutionized our understanding of information theory. Quantum superposition and entanglement constitute a novel type of resource that enables new developments in the fields of communications, computation, metrology, etc., and opens new doors for fundamental physics research [1].

Quantum communications has recently matured from a purely fundamental research area of quantum physics to an applied science with a potentially huge economic impact [2]. The unit of quantum information is the “qubit” (a bit of information “stamped” in a quantum physical property, for instance the polarization of a photon). Moreover, information can be encoded in the correlations between two (or more) particles (e.g. photons or atoms). The properties of “superposition of states” and “entanglement” lead to innovative methods of information processing (e.g. quantum key distribution, QKD; quantum teleportation, QT; quantum dense coding, QDC) and computation, with some algorithms more powerful than their classical counterparts.

At present, the most matured application is QKD. QKD provides means for two (or more) parties to exchange with unconditional security an enciphering key over a quantum channel, since its privacy against an eavesdropper can always be detected. This symmetrical key—after successful distribution—can then be used for encrypting classical information for transmission over a conventional, non-secure communication channel (e.g. telephone line, RF link, optical fibre, optical free-space link).

The utilization of the space segment for distributing quantum keys has been proposed by several groups, [3], [4], [5], [6]. One clear vision of the science community is to test the theory of quantum physics over long distances and to establish a worldwide network for quantum communication—tasks that can only be realized by tackling the additional challenge of bringing concepts and technologies of quantum physics to space [7]. Only the space environment allows performing very long-range experiments of quantum communications and fundamental quantum physics.

This paper is organized as follows. Section 2 summarizes the main results of the European Space Agency (ESA) studies on quantum communications. These studies provided the ideas and concepts for the definition of the proposed Space-QUEST experiment (QUantum Entanglement for Space ExperimenTs) as presented in Section 3. The programmatic roadmap towards this experiment and the related technology development activities are described in Section 4. The potential impact of quantum communications on future space communication systems and on the evolution of global navigation space systems is discussed in Section 5. A number of quantum physics experiments that become only feasible using the added value of the space environment are also discussed. Space environment offers a unique environment compared to ground based experimental facilities (no disturbing influence of atmospheric turbulence, no birefringence/absorption effects like in optical fibres, microgravity conditions, etc.). Section 6 summarizes the technological challenges and programmatic steps towards the implementation of the proposed Space-QUEST experiment.

Section snippets

ESA studies on quantum communications

Since 2002, the following studies have been funded under the General Studies Programme of the European Space Agency:

  • Quantum communications in space (“QSpace”; 2002–2003. Contractors: Vienna University of Technology, Vienna University, QinetiQ and Ludwig Maximilian University).

  • Accommodation of a quantum communication transceiver in an optical terminal (“ACCOM”, 2004. Contractors: Vienna University of Technology, Vienna University, Contraves Space and Ludwig Maximilian University).

  • Experimental

Space-QUEST

Based on the results obtained in the previous studies, a European research consortium led by Vienna University submitted in 2004 the Space-QUEST proposal in the frame of the “Announcement of Opportunity for Life and Physical Sciences and Applied Research Projects 2004” for the ELIPS-2 programme of the European Space Agency [13]. The consortium partners of Vienna University are Vienna University of Technology, Austrian Academy of Sciences, Max Planck Institute, University of Padova, Matera Laser

Programmatic roadmap

The proposed programmatic roadmap for the implementation of the Space-QUEST experiment on the ISS is presented in Fig. 9. Activities are split into system, instrument and module levels. The status of each activity (e.g. completed, on-going, approved proposed) is distinguished by colour. This roadmap encompasses all development activities from the first studies initiated in 2002 until the envisaged launch by end of 2014. The duration of the Space-QUEST experiment is estimated to be 1 year.

The

Telecommunications and navigation

After the successful SILEX flight demonstration, ESA and several European National Agencies (DLR, SSO, French MOD) have maintained the effort in developing the next generation of OCTs with reduced mass, size and power consumption, and increased data transmission rate, aiming at potential optical data relay applications between future LEO satellites/aircrafts and GEO satellites. The integration of a quantum communication transceiver in next generation optical terminals will broaden the range of

Conclusions

The Space-QUEST experiment will be the first step towards a worldwide network for quantum communications. Moving into space enables photonic entanglement to become a physical resource available for quantum experiments (for QKD and beyond) at a global scale. Space-QUEST will validate the key technologies of a quantum communication transceiver (e.g. entangled photon source, weak pulse laser source, single photon counting modules) and will accomplish the first-ever demonstration in space of

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