QSat: Quantum Communication Uplink to a 3U CubeSat Feasibility - - PowerPoint PPT Presentation

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QSat: Quantum Communication Uplink to a 3U CubeSat Feasibility & Design QCrypt 2018 Shanghai, China 27 th August 2018 Sebastian Philipp Neumann Rupert Ursin Group IQOQI Vienna Overview QSat mission setup Why a CubeSat?

SLIDE 1

Q³Sat: Quantum Communication Uplink to a 3U CubeSat – Feasibility & Design

QCrypt 2018

Shanghai, China 27th August 2018 Sebastian Philipp Neumann

Rupert Ursin Group IQOQI Vienna

SLIDE 2

Overview

Q³Sat mission setup
Why a CubeSat?
Satellite design
Choice of orbit
Crucial parameters for high SNR and key rate
Expected performance

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SLIDE 3

Uplink Mission Setup

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Why uplink?

Simple setup on

satellite

Usable for

several protocols

SLIDE 4

Why a CubeSat?

3U: 10x10x34cm, 4kg; ideal for precursor missions

Figures: CubeSat design specification sheet by CalTech and http://spaceflight.com/schedule-pricing/

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SLIDE 5

CubeSat-Design

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SLIDE 6

Block diagram

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SLIDE 7

Preliminary CAD drawing

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SLIDE 8

LEO Orbit Calculations

LEO:

500 km
>30° elevation
night only

 Link duration calculations by group

f Carsten Scharlemann (FH Wiener

Neustadt):

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SLIDE 9

Signal-to-Noise Ratio

Λ: total loss
: pair rate
: optical errors
: coincidence window
: noise count rate
∝ 2

accidental rate

= Λ
ptical error counts

Λ ~ 60dB  low and short are crucial!

> 4.8 for Bell test > 8.8 for QKD

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SLIDE 10

Noise Counts

Dark counts: radiation  tiny 20μm detectors, shielding optional

thermal  passive cooling in total max. 200 cps per detector

E. Anisimova et al.,

“Mitigating radiation damage of single photon detectors for space applications,” EPJ Quantum Technology, vol. 4, no. 1, p. 10, 2017. 04/09/2018 sebastian.neumann@univie.ac.at 10

SLIDE 11

Attitude Control: XACT

Pictures + table from www.bluecanyontech.com

Space heritage, ~40μrad precision without tracking!  In total, ~ 480 cps (zenith) 580 cps (30° elevation)

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Background counts: prop. to field of view (FOV)  has to be as small as possible

(~100μrad)

SLIDE 12

Coincidence Window

for E91 (entangled photon pairs):

– On ground: Superconducting nanowire SPD, 19ps jitter (rms), “no” dark counts – On CubeSat: PDM: 35ps jitter, <5Hz dark counts – Time taggers: 3ps on ground / 20ps on Q³Sat

 = 2

+
+
+
=
for DSP (decoy):

– No detection on ground necessary, just limited by electronics

 =

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SLIDE 13

Trade-Off SNR vs. Rsec

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SLIDE 14

Link Quality

: Fried parameter

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 Total key per year: 13 Mbit  20€/kbit (launch & hardware only)

Fried parameter data taken from http://catserver.ing.iac.es/robodimm/

SLIDE 15

Performance

71 435s link time / year

– 13.0 Mbit / year with decoy – 4.0 Mbit / year with E91

Launch + material cost: 500k€

 20 € / kbit assuming lifetime of 2 years, but low threshold costs

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SLIDE 16

Publication

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SLIDE 17

Co-Authors

Thank you for your attention!

Matthias Fink Thomas Scheidl Siddarth K. Joshi Rupert Ursin

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Carsten Scharlemann Sameh Abouagaga Daanish Bambery Erik Kerstel Mathieu Barthelemy