[Starlink] Free-space Quantum and Optical Time Transfer

[Hesham ElBakoury <helbakoury@gmail.com>]

We had an excellent presentation from David Mitlyng Xairos CEO.

Below you find the summary of David's presentation.

You can access the slides here:
https://drive.google.com/file/d/1QiyRMlK3s4JItvtEyhmXmBcwiEYaUvtM/view?usp=drivesdk

You can access the recording here:
https://youtu.be/eAJD-Ppzydk?is=__iGYlrLpy-Y7N-5

Please forward this email to whoever might be interested in this topic.

Please let us know if you have any questions or comments.

Thank you
Hesham




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Meeting assets for OCP TAP - TSIAW are ready!

Recording
Duration: 01:20:42
Shareable link:
https://opencompute-org.zoom.us/rec/share/vIvW4gYpZH_hOeZKpkaCKqbkoTVjcbxCBBkng9feixpdUAQX-klDcWKeSrkrZluJ.7YHd5iKOItLKZ_N9


Meeting summary

Quick recap

David Mitlyng presented on free space quantum and optical time transfer
technologies at the Time Appliances Working Group meeting, discussing how
his company Kairos is developing systems using entangled photons for secure
and accurate time transfer. He explained the fundamental challenges of
optical systems, including pointing and tracking mechanisms, atmospheric
dispersion, and the need for precise beam alignment, while highlighting
that quantum time transfer offers single-digit picosecond precision through
entangled photon detection and Bell's inequality testing for
authentication. The discussion included technical questions about multi-hub
network challenges, security applications, and comparisons with classical
time transfer methods, with participants sharing insights about related
research at various universities and suggesting potential collaborations
with experts in quantum networking.
Next steps David Mitlyng

   - Send Hesham the slides, recording, and relevant papers from the
   presentation.
   <https://tasks.zoom.us?meetingId=bgu3kxs6RhOivc%2Fy4lACuw%3D%3D&stepId=236eabb4-845f-11f1-98f3-fe55fa5b4ef6>
   - Follow up with David Lariviere to discuss FPGA and low-latency
   hardware collaboration opportunities.
   <https://tasks.zoom.us?meetingId=bgu3kxs6RhOivc%2Fy4lACuw%3D%3D&stepId=236eade1-845f-11f1-9109-fe55fa5b4ef6>
   - Investigate and potentially add energy consumption comparison to
   future parametric studies.
   <https://tasks.zoom.us?meetingId=bgu3kxs6RhOivc%2Fy4lACuw%3D%3D&stepId=236eafb1-845f-11f1-9ba1-fe55fa5b4ef6>
   - Look into hollow-core fiber technology for potential future
   quantum/optical time transfer applications.
   <https://tasks.zoom.us?meetingId=bgu3kxs6RhOivc%2Fy4lACuw%3D%3D&stepId=236eb180-845f-11f1-a2aa-fe55fa5b4ef6>
   - Continue engagement and finalize a CRADA with NIST for quantum
   networking collaboration.
   <https://tasks.zoom.us?meetingId=bgu3kxs6RhOivc%2Fy4lACuw%3D%3D&stepId=236eb33e-845f-11f1-8299-fe55fa5b4ef6>

Hesham

   - Send David Mitlyng the link/agenda for the QIRG/IETF/IATF meetings and
   connect him with relevant contacts (Jean Martinez at UCSB, Don Towsley at
   UMass Amherst, and others mentioned).
   <https://tasks.zoom.us?meetingId=bgu3kxs6RhOivc%2Fy4lACuw%3D%3D&stepId=236ea6d3-845f-11f1-aff1-fe55fa5b4ef6>

Summary Kairos Brainstorming Session Introduction

Hesham welcomed participants to the meeting and noted that over 30 people
had accepted the invitation. David Mitlyng, who was joining from Zurich,
confirmed he would lead a brainstorming session. Myrna, who was supporting
David from Washington State, also joined the meeting. Hesham introduced
David as the CEO of Kairos and expressed his appreciation for David's
knowledge and support for the group before transitioning the meeting to
David's presentation.
Quantum Optical Time Transfer Systems

David Mitlyng presented on optical and quantum time transfer, focusing on
free-space quantum optical time transfer systems. He explained the
fundamental components of time transfer, highlighting the challenges of
transitioning from RF to optical/quantum systems and the importance of both
timing marks and communication of time. The presentation discussed the
potential for a "super GPS architecture" that would use a combination of RF
and optical/quantum links for resilient timing distribution.
RF vs Optical Satellite Links

David Mitlyng explained the differences between RF and optical links for
satellite time transfer, highlighting that optical links provide three
orders of magnitude more precision due to their shorter wavelengths and
better directionality. He discussed how the atmospheric transparency window
affects different frequency bands, with lower frequencies being more
broadband but less directional, while higher frequencies and optical
wavelengths offer better precision but face challenges like atmospheric
obscuration. The presentation covered the fundamental differences in
hardware between RF and optical systems, including antennas, dishes, and
the use of lasers in optical communications.
RF Time Transfer Fundamentals

David Mitlyng explained the fundamentals of RF time transfer, focusing on
GPS as the primary method for global timing distribution. He described how
GPS satellites use multiple stable frequencies and phase changes to
transmit time signals and satellite information to ground receivers, which
can then calculate their time by correlating received signals with their
own generated waveforms. David also noted that while RF time transfer works
well, it faces challenges with signal dispersion and distortion effects
that affect the accuracy of time measurement.
Quantum Time Transfer Challenges

David Mitlyng explained the challenges of time transfer accuracy, noting
that atmospheric dispersion affects both radio frequency and optical
methods, though optical systems can achieve better accuracy through higher
laser power and better signal-to-noise ratio. He described how Kairos
focuses on quantum time transfer using entangled photons, where
measurements of entangled photon pairs can directly determine clock offsets
minus travel time. David also provided historical context about satellite
laser ranging, explaining how NASA used this passive technique in the 1960s
and 1970s to accurately measure satellite distances and determine orbital
paths.
Optical Time Transfer Methods Discussion

David Mitlyng discussed various methods of optical time transfer, including
the T2L2 payload, CubeSat laser infrared crosslink satellites, and the ESA
OPSTAR program. He explained optical frequency combs technology, developed
by John Howell's research group at NIST, which uses evenly spaced,
phase-coherent frequency lines to synchronize distant optical clocks. David
also briefly mentioned quantum time transfer, which leverages entangled
photon sources and single photon detectors.
Entangled Photon QKD Technology

David Mitlyng explained the technology behind entangled photon sources and
their application in quantum key distribution (QKD) and quantum time
transfer. He described how the system uses entangled photon pairs to
securely share encryption keys and synchronize clocks between multiple
locations, achieving picosecond-level precision over distances up to 2
kilometers. The technology has been demonstrated successfully for a US DoD
customer and leverages proven security protocols based on co-founders' 2018
publications.
Quantum Time Transfer Technology Overview

David Mitlyng explained the fundamentals of quantum time transfer
technology, describing how it leverages entangled photons and John Stewart
Bell's mathematical proof to ensure security and authentication. He
detailed the technical challenges of free space optical communications,
including pointing acquisition and tracking, as well as the specific
requirements for time transfer systems such as accounting for Doppler
effects and relativistic corrections. David noted that while optical
communications technology has advanced significantly, with many satellite
constellations now implementing optical links, quantum time transfer
remains a newer field with recent demonstrations, including their own tests
over a couple kilometers and plans for a 2.3 kilometer installation in
Boulder, Colorado.
Quantum Time Transfer and Networks

David presented on quantum time transfer and multi-hub networks, where
Hesham asked about overcoming signal maintenance challenges without
repeaters. David explained that timing inaccuracies would stack up across
multiple network hops and discussed the long-term vision for quantum
networks, noting that quantum repeaters and memory are still very
challenging to develop, with realization potentially 5-10 years away. When
Ankur asked about using quantum time transfer as a security primitive,
David mentioned that while some authentication capabilities exist through
entanglement and Bell's tests, the company is exploring broader
applications of entanglement distribution for security beyond just quantum
time transfer.
Quantum Time Transfer Technology Presentation

David Mitlyng presented on quantum time transfer technology, discussing
their work with entangled photons and fiber-based systems that can achieve
40 femtosecond accuracy over distances up to 40 kilometers. The discussion
revealed ongoing collaborations with NIST and various universities,
including research partnerships with University of Colorado and plans to
establish agreements with UT Arlington and other institutions. Several
participants, including David Lariviere and Christoph Wildfoer, engaged in
technical discussions about signal processing challenges, potential use of
FPGAs, and comparisons with classical protocols like White Rabbit. The
conversation ended with plans to connect David with various researchers in
the quantum networking field and explore potential collaborations,
including work on troposphere measurements and energy consumption
comparisons between different time transfer methods.

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