Mark Mitchison
@mitchison.bsky.social
Theory of Controlled Quantum Systems | @royalsociety.org University Research Fellow @ King’s College London | Editor @quantum-journal.bsky.social & New Journal of Physics | He/him | posts ≈ 60% science/30% politics/11% nonsense
We find strong system-bath coupling can suppress current fluctuations in a driven quantum system, allowing violation of thermodynamic uncertainty relations! We understand this in terms of the system hybridising with a collective environment mode, which leads to antibunching in the current statistics
October 18, 2025 at 2:51 PM
We find strong system-bath coupling can suppress current fluctuations in a driven quantum system, allowing violation of thermodynamic uncertainty relations! We understand this in terms of the system hybridising with a collective environment mode, which leads to antibunching in the current statistics
Awesome to have Kavan Modi visit us at King’s and talk about his work characterising correlated errors in quantum computers, using Quantum Process Tensor Tomography 🤩
October 1, 2025 at 5:06 PM
Awesome to have Kavan Modi visit us at King’s and talk about his work characterising correlated errors in quantum computers, using Quantum Process Tensor Tomography 🤩
So many great talks at Fundamental Limits of Quantum Technologies already, and many more yet to come! Here’s Shane Dooley of DIAS telling us about metrology using many-body quantum systems 🤩
www.aspects-quantum.com/flqt2025
@aspects-quantum.bsky.social
www.aspects-quantum.com/flqt2025
@aspects-quantum.bsky.social
August 26, 2025 at 11:06 AM
So many great talks at Fundamental Limits of Quantum Technologies already, and many more yet to come! Here’s Shane Dooley of DIAS telling us about metrology using many-body quantum systems 🤩
www.aspects-quantum.com/flqt2025
@aspects-quantum.bsky.social
www.aspects-quantum.com/flqt2025
@aspects-quantum.bsky.social
Fresh on arXiv! arxiv.org/abs/2508.16375 By casting detectors as autonomous thermal machines, we uncover the link between entropy production and the detector’s efficiency, timing jitter, dead time and dark counts. Outstanding work by Manu Schwarzhans with my @aspects-quantum.bsky.social friends ❤️
August 26, 2025 at 6:47 AM
Fresh on arXiv! arxiv.org/abs/2508.16375 By casting detectors as autonomous thermal machines, we uncover the link between entropy production and the detector’s efficiency, timing jitter, dead time and dark counts. Outstanding work by Manu Schwarzhans with my @aspects-quantum.bsky.social friends ❤️
I very much appreciate a well organised metro map (Singapore MRT)
July 17, 2025 at 1:06 AM
I very much appreciate a well organised metro map (Singapore MRT)
Very proud and honoured to kick off QTD Singapore 2025 with an invited talk! I attended my first QTD conference in Porquerolles 10 years ago: a career-changing moment where I found my community and cemented my love for the topic 🤓 I hope some of this year’s attendees get as much out of it as I did!
July 8, 2025 at 1:53 PM
Very proud and honoured to kick off QTD Singapore 2025 with an invited talk! I attended my first QTD conference in Porquerolles 10 years ago: a career-changing moment where I found my community and cemented my love for the topic 🤓 I hope some of this year’s attendees get as much out of it as I did!
How to compute heat statistics at strong coupling? We introduce a heat operator, casting two-point measurement statistics as a simple expectation value. This makes it easy to tackle using tensor network algorithms eg. the chain mapping. Many exciting applications for this one! 🤩
April 16, 2025 at 8:22 PM
How to compute heat statistics at strong coupling? We introduce a heat operator, casting two-point measurement statistics as a simple expectation value. This makes it easy to tackle using tensor network algorithms eg. the chain mapping. Many exciting applications for this one! 🤩
Happy World Quantum Day everyone!
April 14, 2025 at 9:19 AM
Happy World Quantum Day everyone!
Today I start a new job at King’s College London! I’m now a Proleptic Senior Lecturer and Royal Society University Research Fellow in the Dept. of Physics @kingsnmes.bsky.social I’m delighted to return home after >8 years working abroad, and very excited to start this new chapter in my career!
April 1, 2025 at 4:33 PM
Today I start a new job at King’s College London! I’m now a Proleptic Senior Lecturer and Royal Society University Research Fellow in the Dept. of Physics @kingsnmes.bsky.social I’m delighted to return home after >8 years working abroad, and very excited to start this new chapter in my career!
Extremely proud to be holding a beautifully bound copy of the thesis of Oisín Culhane, my first PhD student!
March 26, 2025 at 2:09 PM
Extremely proud to be holding a beautifully bound copy of the thesis of Oisín Culhane, my first PhD student!
Pauli Erker giving a wonderful invited talk on the autonomous quantum processing unit arxiv.org/abs/2402.00111, part of an inspiring session on Time in Quantum Mechanics and Thermodynamics at #APSSummit2025
March 20, 2025 at 8:55 PM
Pauli Erker giving a wonderful invited talk on the autonomous quantum processing unit arxiv.org/abs/2402.00111, part of an inspiring session on Time in Quantum Mechanics and Thermodynamics at #APSSummit2025
At #APS watching Simon Sundelin nailing his talk on our @aspects-quantum.bsky.social collaboration 😍
March 19, 2025 at 8:14 PM
At #APS watching Simon Sundelin nailing his talk on our @aspects-quantum.bsky.social collaboration 😍
These differences appear to persist in the thermodynamic limit: finite-size scaling shows the entanglement variance for falls off exponentially only in chaotic models. This suggests that basically any local multi-time intervention on a large chaotic many-body system generates maximal entanglement
February 22, 2025 at 2:05 PM
These differences appear to persist in the thermodynamic limit: finite-size scaling shows the entanglement variance for falls off exponentially only in chaotic models. This suggests that basically any local multi-time intervention on a large chaotic many-body system generates maximal entanglement
Not only does this recover several previously studied chaos and complexity measures, it contains a bunch of new information in its higher moments! Chaotic many-body systems generate a distribution closely matching the Haar-random process, unlike integrally/localised models
February 22, 2025 at 2:05 PM
Not only does this recover several previously studied chaos and complexity measures, it contains a bunch of new information in its higher moments! Chaotic many-body systems generate a distribution closely matching the Haar-random process, unlike integrally/localised models
But chaos is identified by the complexity of the output states as well as the time series. We capture this with the projected process ensemble: an ensemble of states conditioned on multi-time interventions. This is like the projected ensemble studied in deep thermalisation, but for quantum processes
February 22, 2025 at 2:05 PM
But chaos is identified by the complexity of the output states as well as the time series. We capture this with the projected process ensemble: an ensemble of states conditioned on multi-time interventions. This is like the projected ensemble studied in deep thermalisation, but for quantum processes
Quantum chaos does not have a unique definition. One approach in classical physics is to think about the complexity of the trajectories in phase space over time — the dynamical entropy. Operationally, a trajectory of a quantum system is a sequence of measurements, described by a process tensor
February 22, 2025 at 2:05 PM
Quantum chaos does not have a unique definition. One approach in classical physics is to think about the complexity of the trajectories in phase space over time — the dynamical entropy. Operationally, a trajectory of a quantum system is a sequence of measurements, described by a process tensor
Our paper shows this won't work! Any quantum clock must produce macroscopic amounts of entropy, in order to amplify its ticks into a classical record of time. The entropy produced by the measurement dwarfs that needed to generate ticks, and this dissipation can even drive the clock by itself
4/6
4/6
February 4, 2025 at 6:52 PM
Our paper shows this won't work! Any quantum clock must produce macroscopic amounts of entropy, in order to amplify its ticks into a classical record of time. The entropy produced by the measurement dwarfs that needed to generate ticks, and this dissipation can even drive the clock by itself
4/6
4/6
Latest preprint from the ASPECTS consortium! arxiv.org/abs/2502.00096 Experiments by the amazing @naresgroup.bsky.social and theory by @mathsmire.bsky.social of @quitphysics.info We measured the entropy cost of generating and recording ticks in a microscopic clock
1/6 🧵👇
1/6 🧵👇
February 4, 2025 at 6:52 PM
Latest preprint from the ASPECTS consortium! arxiv.org/abs/2502.00096 Experiments by the amazing @naresgroup.bsky.social and theory by @mathsmire.bsky.social of @quitphysics.info We measured the entropy cost of generating and recording ticks in a microscopic clock
1/6 🧵👇
1/6 🧵👇
I’m probably late to this party, but can we please talk about APS butchering their own website? Look at the formatting in PRL’s author “style guide” for example… are those supposed to be section headings?! Link previews in Slack no longer work either. Why did they do this?!
January 25, 2025 at 1:13 PM
I’m probably late to this party, but can we please talk about APS butchering their own website? Look at the formatting in PRL’s author “style guide” for example… are those supposed to be section headings?! Link previews in Slack no longer work either. Why did they do this?!
A proud moment as my first PhD student, Oisín Culhane, defends his excellent thesis on the quantum and stochastic thermodynamics of tiny wobbly things 😍
December 19, 2024 at 2:03 PM
A proud moment as my first PhD student, Oisín Culhane, defends his excellent thesis on the quantum and stochastic thermodynamics of tiny wobbly things 😍
Giving a seminar in the Michael Berry Lecture Theatre @bristoluni.bsky.social! ❤️🫐
December 3, 2024 at 4:35 PM
Giving a seminar in the Michael Berry Lecture Theatre @bristoluni.bsky.social! ❤️🫐
🚨new paper🚨 out today! We use the same kind of artificial intelligence model that underpins ChatGPT for quantum feedback control! The “attention” mechanism that lets generative AI understand context also helps us deal with memory effects in the measurement record!
arxiv.org/abs/2411.19253
arxiv.org/abs/2411.19253
December 2, 2024 at 9:45 AM
🚨new paper🚨 out today! We use the same kind of artificial intelligence model that underpins ChatGPT for quantum feedback control! The “attention” mechanism that lets generative AI understand context also helps us deal with memory effects in the measurement record!
arxiv.org/abs/2411.19253
arxiv.org/abs/2411.19253
Ok BlueSky let’s do this! I’m a theoretical physicist interested in how very tiny ⚛️ or very cold 🥶 bits of matter interact with their surroundings: physicists call these *open quantum systems*. I’m going to be posting on my research and public outreach activities, plus the odd bit of fun/nonsense 🤪
December 2, 2024 at 9:34 AM
Ok BlueSky let’s do this! I’m a theoretical physicist interested in how very tiny ⚛️ or very cold 🥶 bits of matter interact with their surroundings: physicists call these *open quantum systems*. I’m going to be posting on my research and public outreach activities, plus the odd bit of fun/nonsense 🤪