Rob Malaney UNSW
Transcript of Rob Malaney UNSW
Quantum Communications with Cubesats
UNSW
10 July 2018
Rob Malaney UNSW
Image: Zeilinger 2000
Quantum Communications (Malaney, Globecom 2016)
QKD (revisited) – Product Status
ID Quantique.com
•Provide secured quantum keys for any encryption device
•Scalable: one quantum key server can distribute keys for up to 100Gbps of data
•Fully automated key exchange with continuous key renewal
•Integrated entropy source based on a •Quantum Random Number Generator
•Adaptable: Works on dark fibre and •WDM networks
~100km in Fibre Quantum Key Rate 1MB/s at 50km (Fibre)
Toshiba.com “Decoy” rate
IDQuantique, Toshiba, MagiQ, SeQureNet, QinetiQ, Quintessence (CV states)
4) Emerging Apps –QKD (revisited) (Malaney, Globecom 2016)
QKD (revisited) Status - Free Space
Lo et al 2014
a, First free-space demonstration of QKD19 realized two decades ago over a distance of 32 cm. The system uses a light-emitting diode (LED) in combination with Pockels cells to prepare and measure the different signal states. b, Entanglement-based QKD set-up connecting the two Canary Islands La Palma and Tenerife6. The optical link is 144 km long. OGS, optical ground station; GPS, Global Positioning System; PBS, polarizing beamsplitter; BS, beamsplitter; HWP, half-wave plate. c, Schematic of a decoy-state BB84 QKD experiment between ground and a hot-air balloon20.
4) Emerging Apps –QKD (revisited) (Malaney, Globecom 2016)
Large Scale Systems –
Towards the Quantum Internet Two Recent Important Network Results
Rob Malaney
Hefei, China
Sun et al 2016. Calgary, Canada
Valivarthi et al 2016.
4) Emerging Apps – The Quantum Internet (Malaney, Globecom 2016)
Why Quantum Communications via Space• Quantum Communications is the next Communication Frontier
• China has recently demonstrated all forms of Quantum Communication via satellite are feasible
• Long-range Quantum Communication via satellite will enable the Quantum Internet
• The Quantum Communication will provide for the most secure communication systems known – secured solely by the laws of physics
GEO ORBIT
GEO spacecraft Alphasat I-XL 38000km
Quantum-limited measurements of optical signalsfrom a geostationary satelliteGÜNTHNER e atl 2018
GPS ORBIT
GLONASS Reflector spacecraft 20000km
Towards Quantum Communication from Global Navigation Satellite SystemCalderaro et al 2018
MICIUS (China)
GLONASS Reflector spacecraft 20000km
Satellite-relayed intercontinental quantum networkSheng-Kai Liao et al 2018
QKD via Nano Satellite
DEMONSTRATING MINIATURISED, ENTANGLED PHOTON-PAIR SOURCES ON BOARD NANO SATELLITES TO ENABLE FUTURE QKD MISSIONS R. C.M.R.B. Chandrasekaraa 2018
Table 1 | Specifications of the SOTA and loss characteristics of the link and the OGS.
Tx2 Tx3 CommentsSpecifications of SOTAPolarization Linear Linear Ellipticity <0.1°Wavelength (μm) 0.8 0.8 At 25 °C, centre wavelength varies at 0.1 nm °C–1
Wavelength width (nm) 0.2 0.2 Measured at −3 dB full widthClock frequency (MHz) 10 or 1 10 or 1 SelectableIntensity (MWsr−1) 2.68 × 10−3 3.30 × 10−3 Average power at 10 MbpsMean photon number per pulse 2.34 × 108 1.78 × 108
Beam divergence (μrad) 970 880 Measured at −3 dB full widthPointing loss (dB) −1.5 −1.9 Owing to small misalignment of Tx2/3 from the direction
of pointing beam from Tx4Transmit aperture (mm) <5 <5SOTA optical loss (dB) −0.2 −0.2
Loss characteristics of the link and the receiver for a 53° elevation angleAtmospheric attenuation (dB) −3.55 −3.55 Estimated with the code MODTRAN (Spectral Sciences)Space coupling loss to the receiver telescope (dB) −57.8 −56.9 Evaluated for a SOCRATES–OGS distance
of 802 km at 22:59:00 JSTReceiver’s telescope loss (dB) −2.68 −2.68 −1 dB due to primary mirror and −1.68 dB due to secondary
and tertiary mirrorsQuantum receiver loss (dB) −14.5 −14.5 Evaluated by using star light (Supplementary Table 1)Total loss budget (dB) −78.5 −77.7
Primary mirror
Tertiarymirror
Secondarymirror
1 mtelescope
SOTA
SOCRATES
SPCM2SPCM1
SPCM3
SPCM4
Lens
Lens
LensLens
Lens
PD
IRtrackingcamera
BS
PBS
PBS
DM
Iris
Mirror
Mirror
Collimatinglens
×10 beamreducer
HWP45°
Lens
Filter
BS
Tx2/3 path(0.8 µm)
Tx4 path(1.5 µm)
Nasmythbench
d
z
x
y
SOTAa b
−44°
z
yx
Tx3
Tx2
Tx2 and Tx3
c
Figure 1 | Transmitter and receiver systems. a, Picture of the SOTA (18 cm width × 11 cm depth × 27 cm height). b, Configuration of the two linearlypolarized laser diodes Tx2 and Tx3 in the SOTA. c, Receiver telescope. d, Quantum receiver. DM; dichroic mirror; PD, photodetector; IR, infrared;BS, beamsplitter; PBS, polarizing beamsplitter; HWP, half-wave plate; SPCM, single-photon counter module. In the NICT OGS, incident light reflected by theprimary and secondary mirrors passes through a tertiary mirror (made of aluminium to minimize linear polarization deterioration). The beam after thetertiary mirror has a width of 3 mm and is guided towards the quantum receiver installed at the Nasmyth bench of the telescope. A 1.5-μm-wavelengthcircularly polarized beam from the SOTA was used for satellite tracking and was separated from the 0.8-μm-wavelength light using a dichroic mirror in thequantum receiver. This 1.5 μm beam was then guided to a PD and monitored using an IR camera. The quantum receiver consists of BSs, PBSs and a HWP,ending with four ports, where four SPCMs based on Si avalanche photodiodes were used as detectors after coupling the beams to multimode optical fibresusing converging lenses. Received photon counts were then time-tagged by a time-interval analyser (timing resolution of 1 ps), generating a time-taggedphoton-count sequence for each SPCM.
NATURE PHOTONICS DOI: 10.1038/NPHOTON.2017.107 ARTICLES
NATURE PHOTONICS | VOL 11 | AUGUST 2017 | www.nature.com/naturephotonics 503
© 2017 Macmillan Publishers Limited, part of Springer Nature. All rights reserved.
Conclusions
Quantum Communications is an exciting new area for engineers – it is here to stay. It will deliver the ultimate cyber-security solutions to next-generation networks. There are many real-world problems looking for real-world engineering solutions. Specific engineering challenges highlighted here include - Large-scale City-wide Networks Space-based Communications The Global Quantum Internet New Multiplexing Schemes (OAM) Next-Generation (6G) Wireless Communications
Nano Satellites Challenges – seem biggest
5) Conclusions (Malaney, Globecom 2016)