New preprint out with @marcotomamichel.bsky.social ! Projections with Respect to Bures Distance and Fidelity: Closed-Forms and Applications scirate.com/arxiv/2602.1... We derive simple closed-form solutions for fidelity / Bures/purified distance projections to various sets of interest.

Quantum Toolbox (15): Relating Relative Entropy and Fidelity (1/6):

Quantum Toolbox (15): Relating Relative Entropy and Fidelity (1/6):

Quantum Toolbox (14): Quantum Pinsker Inequality (1/6)

Quantum Toolbox (13): Matrix Geometric Mean (1/7)

Quantum Toolbox (13): Matrix Geometric Mean (1/7)

The last defence this year 🥳💐 Congratulations to Hu Yanglin for successfully defending his thesis, "Quantum Oblivious Transfer: Bounds and Applications", on how to protect privacy with quantum technologies and how to learn quantum systems efficiently. He was advised by @marcotomamichel.bsky.social

Quantum Toolbox (12): Bretagnolle-Huber Inequality (1/6)

Quantum Toolbox (11): Generalized Operator Schwarz Inequality (1/6)

Quantum Toolbox (10): Uhlmann's Theorem (1/6)

Quantum Toolbox (9): Sample Complexity Lower Bounds via Mutual Information (1/6)

Congratulations to CQT Principal Investigator @marcotomamichel.bsky.social who has been awarded the prestigious National Research Foundation (NRF) Investigatorship. He receives support for a five-year programme of research starting in August 2025. buff.ly/QrAJWkn

🍾💐 Celebrating a successful thesis defence by Josep Lumbreras Zarapico!! 🍉🧀🍪 Advised by @marcotomamichel.bsky.social, Josep defended his thesis "Bandits Roaming Hilbert Space". He will next join Mile Gu’s group as a research fellow. Congrats and all the best, Dr Josep!

Quantum Toolbox (8): Hadamard's Three-Lines Theorem (1/6)

👏💐Congrats to PhD student Roberto Rubboli who successfully defended his thesis, "Optimization and Additivity of Quantum Relative Entropies"! He was advised by @marcotomamichel.bsky.social‬. Next, he will join the group of Daniel Stilck França at the University of Copenhagen. All the best Dr Roberto!

"I’m interested in how we create quantum primitives which ensure security of data," says Tristan Philippe, one of the first PhD students to start research at CQT under Singapore's National Quantum Scholarships Scheme 🇸🇬 🎓 Read his interview: bit.ly/3Zc95KK

Quantum Toolbox (7): Continuity of the von Neumann Entropy (1/6)

We are happy to share our work in classical distribution testing "Testing (Conditional) Mutual Information" (arxiv.org/abs/2506.03894), which was recently accepted at COLT 2025. (1/6)

Quantum Toolbox (6): Hoeffding's Inequality (1/7)

Our work "Learning pure quantum states (almost) without regret" (arxiv.org/abs/2406.18370) has received an important extension! We connect the notion of regret with the disturbance caused by projective measurements to efficiently learn pure states (almost) without disturbance. (1/3)

Quantum Toolbox (5): Cauchy-Schwarz Inequality (1/6)

Quantum Toolbox (4): Jordan's Lemma (1/6)

Quantum state-agnostic work extraction (almost) without dissipation: We are excited to share a new application of the multi-armed quantum bandit framework—this time in quantum thermodynamics!

We were excited to host @christophhirche.bsky.social as an outgoing MSCA postdoc here in Singapore and are ready to host again whenever scientific interests align.

We are currently looking for a postdoc. If you are intrigued by Singapore and CQT (and you should be) and have experience in mathematical aspects of quantum information, especially with information measures, quantum cryptography or learning theory, get in touch! careers.nus.edu.sg/job/Research...

Quantum Toolbox (3): Data-Processing Inequality (1/7)

Quantum Toolbox (2): Schur-Weyl Duality (1/6)

Quantum Toolbox (1): Jensen's Inequality (1/6)

In a series of posts, we aim to present a set of essential tools & techniques that we believe every aspiring quantum information theorist should have in their toolbox. 🧰🛠️ We think these techniques will also be useful for researchers in adjacent fields. All tools will be linked in this thread: 🧵

The consecutive measurement theorem makes rigorous and robust the intuition that if there exist measurements that succeed with high probability to guess various properties of a quantum system then two consecutive such measurements can be used to deduce two properties with high probability as well.

This birthday I received a very special present from my group, a quantum information theory toolbox! Follow @qit-cqt.bsky.social as we go through the tools one by one!

The official account of the Quantum Information Theory group at the Centre for Quantum Technologies, Singapore.