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===[[QKD receiver characterization (Polarization)]]===
=== [[QKD receiver characterization (Polarization)]] ===


Calibrated polarization-state generator to characterize polarization analysis modules in QKD receiver and rigorously quantify the impact on secure key rates.
Calibrated polarization-state generator to characterize polarization analysis modules in QKD receivers and rigorously quantify the impact on secure key rates.


'''Team members:''' Elias X. Huber, various AI agents (open to join forces with other humans as well, you can reach me at elias.x.huber[at typical nus sufix]; please note though that I will likely do the experiment at UTown (CREATE Tower), my schedule tends to be a bit inflexible for team-work, and I am a theorist with no lab experience).
'''Team members:''' Elias X. Huber, various AI agents (open to join forces with other humans as well, you can reach me at elias.x.huber[at typical nus sufix]; please note though that I will likely do the experiment at UTown (CREATE Tower), my schedule tends to be a bit inflexible for team-work, and I am a theorist with no lab experience).


QKD receivers are subject to imperfections which, if not adequately considered in security proofs, may compromise the security of generated secret keys. This project considers receivers that measure polarization in the Pauli <math>Z</math> and Pauli <math>X</math> bases (a passive-basis-choice "BB84 measurement").
Such a receiver consists of a polarization analysis module (PAM) followed by single-photon detectors. A simple schematic is given below.


<pre>
=== [[Control and measurement in the bosonic cQED system]] ===
                    ┌── PBS ── H ── det H    (Z / rectilinear arm)
Using control and measurement methods to characterize a dispersively coupled single superconducting cavity and single transmon qubit system, with a thorough review of the theories and experimental techniques behind it.
                    │      └── V ── det V
channel ── PC ── BS ┤
                    │      ┌── + ── det +    (X / diagonal arm)
                    └── HWP ┤
                    ~22.5° └── − ── det −
</pre>


Light from the quantum channel (single-mode fibre, optionally after a polarization controller PC) is split by a non-polarizing beam splitter (BS) into a rectilinear (<math>H/V</math>) arm and a diagonal (<math>+/-</math>) arm. An HWP near <math>22.5^\circ</math> rotates the <math>X</math>-arm basis before its PBS. The four ports are monitored by detectors labelled <math>H,V,+,-</math>.
'''Team members:''' Grace Pang and Seungwon Jin


===[[Multi-tone RFSoC driver for an AOM]]===
A multi-tone RF synthesizer on an RFSoC board to drive an acousto-optic modulator(AOM).


Imperfections such as arm-dependent loss, biased beam-splitting ratios, or a low PBS extinction ratio may leak (partial) key information to an adversary or enable active attacks that bias detectors. As part of my work/PhD, I have been working on (theoretical) methods to integrate PAM characterization data into a QKD security proof. This project aims to build '''calibrated polarization preparation''' and characterize first a self-assembled PAM and subsequently the PAM of a real QKD receiver.
'''Team members:''' Mani Aarthy


===[[Placeholder for project title]]===
TBD.
'''Team members''' Wang Ziyan and Wu Jinbin
===[[Laser Phase Offset Lock]]===
We plan to implement an offset lock to phase stabilize a pair of External Cavity Diode Lasers (ECDL) at a fixed offset of 6.8 GHz, matching the Rb87 ground state hyperfine transition.
'''Team members:''' Bibhuti Thapa, Xu Zifang, Chan Jun Jie
===[[Home-Built ECDL and Optical Sideband Generation]]===
The project includes the construction and characterization of a Littrow ECDL, microwave-driven EOM sideband generation near 6.8 GHz, and optical beat-note techniques for relative frequency stabilization with an existing Rb87 trapping laser.
'''Team member:''' Liu Yiming
===[[Thermal Drift Compensation via RF and DC Feedback for Thermal Device Control Applications]]===
We plan to calibrate a thermally tunable microring resonator, compensate TEC-induced thermal drift using DC feedback, and evaluate gesture-image reconstruction through the AC channel.
'''Team members:''' Huang He, Ding Jiahao, Xu Anbang
===[[Measurement of Coherent States in Phase Space]]===
'''Team members:''' Lim Zi Way, Raghav Sah, Shawn Liew Hong Wei
===[[Design and Construction of a Confocal Microscope for Photonic Material Characterization]]===
'''Team members:''' Kim Sihyung, Ankush Sharma, Liang Shuyi


==Resources==
==Resources==
Line 40: Line 63:
===Recommended literature===
===Recommended literature===
* Bahaa E. A. Saleh, Malvin Carl Teich: Fundamentals of Photonics, Wiley; available as [https://libproxy1.nus.edu.sg/login?url=https://search.ebscohost.com/login.aspx?direct=true&db=nlebk&AN=26193&site=ehost-live&ebv=EB&ppid=pp_Cover  e-book in NUS]. Excellent reference book for many optics topics.
* Bahaa E. A. Saleh, Malvin Carl Teich: Fundamentals of Photonics, Wiley; available as [https://libproxy1.nus.edu.sg/login?url=https://search.ebscohost.com/login.aspx?direct=true&db=nlebk&AN=26193&site=ehost-live&ebv=EB&ppid=pp_Cover  e-book in NUS]. Excellent reference book for many optics topics.
* Mark Fox: Quantum Optics: An Introduction, Oxford University Press; available as [https://libproxy1.nus.edu.sg/login?url=https://search.ebscohost.com/login.aspx?direct=true&scope=site&db=nlebk&db=nlabk&AN=208564 e-book in NUS]. Nice book on traditional quantum optics topics.
* Christopher C. Davis: Lasers and electro-optics, Cambridge; available as [https://libproxy1.nus.edu.sg/login?url=https://dx.doi.org/10.1017/CBO9781139016629 e-book in NUS]. Good overall book on optics-related aspects useful for controlling quantum systems.
===Recorded classes===
===Recorded classes===


Line 68: Line 94:
| Transverse mode structure, optical coating basics
| Transverse mode structure, optical coating basics
|  
|  
|-
| 14.9.2026
| [https://youtu.be/Lwt6eJe12h0 Homo- and heterodyning basics]
| Radiofrequency origins of mixers, optical version
| any quantum optics text (e.g. Mark Fox, see above)
|-
| 15.9.2026
| [https://youtu.be/2nhP60FKstQ Optical Modularors 1]
| Mostly Electro-optical modulators, some LCD as well
| e.g. Davis: Laser and Electro-optics
|-


|}
|}

Latest revision as of 14:19, 24 September 2026

Wiki page for course QT5201U (Quantum control technology) - AY2026/27S1

This will be the place for documenting projects. To be able to write something to this wiki, we need to create a user login manually. If you have not yet created an account, do let me know - Christian.

Next class: Mon 17 Aug 2026 in the seminar room S15 level 5.

Project pages

One sentence, describing what this project is is about.

Team members: A, B, C


Calibrated polarization-state generator to characterize polarization analysis modules in QKD receivers and rigorously quantify the impact on secure key rates.

Team members: Elias X. Huber, various AI agents (open to join forces with other humans as well, you can reach me at elias.x.huber[at typical nus sufix]; please note though that I will likely do the experiment at UTown (CREATE Tower), my schedule tends to be a bit inflexible for team-work, and I am a theorist with no lab experience).


Using control and measurement methods to characterize a dispersively coupled single superconducting cavity and single transmon qubit system, with a thorough review of the theories and experimental techniques behind it.

Team members: Grace Pang and Seungwon Jin

A multi-tone RF synthesizer on an RFSoC board to drive an acousto-optic modulator(AOM).

Team members: Mani Aarthy

TBD. Team members Wang Ziyan and Wu Jinbin


We plan to implement an offset lock to phase stabilize a pair of External Cavity Diode Lasers (ECDL) at a fixed offset of 6.8 GHz, matching the Rb87 ground state hyperfine transition.

Team members: Bibhuti Thapa, Xu Zifang, Chan Jun Jie


The project includes the construction and characterization of a Littrow ECDL, microwave-driven EOM sideband generation near 6.8 GHz, and optical beat-note techniques for relative frequency stabilization with an existing Rb87 trapping laser.

Team member: Liu Yiming


We plan to calibrate a thermally tunable microring resonator, compensate TEC-induced thermal drift using DC feedback, and evaluate gesture-image reconstruction through the AC channel.

Team members: Huang He, Ding Jiahao, Xu Anbang

Team members: Lim Zi Way, Raghav Sah, Shawn Liew Hong Wei


Team members: Kim Sihyung, Ankush Sharma, Liang Shuyi

Resources

Some hopefully useful references should go here.

  • Bahaa E. A. Saleh, Malvin Carl Teich: Fundamentals of Photonics, Wiley; available as e-book in NUS. Excellent reference book for many optics topics.
  • Mark Fox: Quantum Optics: An Introduction, Oxford University Press; available as e-book in NUS. Nice book on traditional quantum optics topics.
  • Christopher C. Davis: Lasers and electro-optics, Cambridge; available as e-book in NUS. Good overall book on optics-related aspects useful for controlling quantum systems.

Recorded classes

Date Topic Description Reference
17.8.2026 Paraxial ray optics A recap of how to deal with classical ray optics through ABCD matrices Saleh, Teich: Fundamentals of Photonics
18.8.2026 Paraxial wave optics Working towards Gaussian beams found with lasers... same as above
24.8.2026 Optical cavities 1 Fabry-Perot, simple 1D dimensional
25.8.2026 Optical cavities 2 Transverse mode structure, optical coating basics
14.9.2026 Homo- and heterodyning basics Radiofrequency origins of mixers, optical version any quantum optics text (e.g. Mark Fox, see above)
15.9.2026 Optical Modularors 1 Mostly Electro-optical modulators, some LCD as well e.g. Davis: Laser and Electro-optics

Complete playlist: https://www.youtube.com/playlist?list=PLN-Fk1m9cTD4

Previous version of this course wiki

Getting started

Consult the User's Guide for information on using the wiki software.

  • MediaWiki FAQ
  • Math can be entered in LaTeX style: <math>r^2=\sqrt{x^2+y^2}</math> renders as r2=x2+y2
  • Should you miss any module or functionality of this wiki, please contact me (Christian Kurtsiefer).