Jake Xuereb

jake

About

Hi! I'm Jake, a fledgling quantum physicist from Malta. I once ran a private education start-up called LearnD, but I think I'm involved in other start-ups elsewhere in spacetime.

I am a PhD Student in the QUIT Group at the TU Wien's Atominstitut in Vienna, supervised by the entangled anarchist.

Broadly, I'm interested in what fundamental truths Quantum Information can tell us about the Universe and the foundations of Physics all the way from gravity to measurement, and how Quantum Computing can be the tool through which these truths are uncovered.

Before this I was a research Master's student working within the Quantumalta Group at the University of Malta funded by an Endeavour Scholarship part of which I spent as a visiting research student with CATS at UCD and QuSys at Trinity College in Dublin.

My Curriculum-Vitae is available on request.

I live at and am part of Wohn Projekt Wien, a project trying to examine how to build sustainable human communities in large cities.

I'm trying to get back into running right now.

If you'd like to, you can read about how I find meaning in being alive, here. I also recently wrote a list of things I want to try to do outside of physics as a way to make sure I don't get too consumed by this work I love doing, you can read that here.

Should you wish to support me you can send me cryptocurrency at 0x3D4FA832f5a9C02709A5d961E537DBB309A1F3ab

'The eye--it cannot choose but see;
We cannot bid the ear be still;
Our bodies feel, where'er they be,
Against, or with our will.

From "Expostulation & Reply" by William Wordsworth.

Oh! If you're confused that's probably because you're looking for André Xuereb, the first Maltese quantum physicist, my undergrad & MSc supervisor, quantum optomechanical legend and Malta's Ambassador for Digital Affairs amongst other things. NO, we are NOT related, Malta is just that small.

Research

time

Here is a list of manuscripts and publications that I have worked on in reverse chronological order together with a summary and if available slides, recording of a talk and press related to the works.

If you'd like to discuss these ideas or you'd like me to give a talk about related work please do reach out.

The main questions I've been interested in so far have been related to the physics of computation and the foundations of quantum thermodynamics. But I am generally interested in questions and ideas spanning all of quantum theory. I am happy to mentor undergraduate students interested in these topics, especially if you're a Maltese person making your first quantum steps.

6. What resources does an agent need to acquire knowledge in Quantum Thermodynamics?

arXiv:2410.18167 (2024) | with Ale de Oliveira Jr., Fabien Clivaz, Pharnam Bhakshinezhad and Marcus Huber

What does it mean for an agent to have knowledge of a state in quantum thermodynamics? And if they only have partial knowledge how does it impact their ability to carry out tasks with access to a sysem in that state? In this work we take the perspective that an agent has knowledge of a state if they are able to reconstruct it with partial knowledge being approximate reconstruction. To answer these questions we build a bridge from coarse grained state estimation to a unitary protocol where a dimensionally constrained probe system is correlated with a larger system in an unknown state, such that using the information in the probe the state of the system is reconstructed in a quantum memory. We find results with close connection to quantum cloning and use majorisation theory to make statements about the possibility of exact reconstruction and apply our insights to work extraction and state transformation in quantum thermodynamics.

5. Emergence of a second law of thermodynamics in isolated quantum systems

arXiv:2406.01677 (2024) | Florian Meier, Tom Rivlin, Tiago Debarba, Myself, Marcus Huber, Maximilian P. E. Lock

This work examines how to recover a 2nd law of quantum thermodynamics in the context of closed unitary quantum evolution. We consider the setting of equilibration on average and examine which for which observables the expectation values of a freely evolving state approach those of the equilibrium state. Our main tool here is the entropy of the distribution of expectation values or Shannon Entropy of the Observable which we use to derive bounds on when systems should equilibriate and on their fluctuations. We recover the 2nd law as a statement about the increase of this Shannon Observable Entropy together with the past hypothesis.

time

4. Autonomous Quantum Processing Unit: What does it take to construct a self-contained model of quantum computation?

arXiv:2402.00111 (2024) | Florian Meier, Marcus Huber, Pauli Erker and Myself

This paper presents a framework called the autonomous Quantum Processing Unit, an autonomous thermal machine formed of a quantum clock, computational target state, and semi-classical states that encode an algorithm one wishes to execute. The framework examines the thermodynamic cost of computation and how physics limits the speed of quantum computation.

3. Quantum Coding with Finite Thermodynamic Resources

arXiv:2311.14561 (2023) | with Tiago Debarba, Marcus Huber, and Paul Erker

This paper investigates the thermodynamic resources required for an agent to compress messages of pure states. The study examines the costs and limitations imposed by finite thermodynamic resources on quantum coding.

time

2. The Impact of Imperfect Timekeeping on Quantum Control

arXiv:2001.03685 (2023) | Phys. Rev. Lett. 131, 160204 | with Paul Erker, Florian Meier, Mark Mitchison, and Marcus Huber

This paper examines how the quality of the clock an agent has access to limits their ability to perform quantum computations and cool quantum systems. The study looks at the physical constraints and energetic costs of computation imposed by imperfect resources like faulty clocks.

1. Deterministic Quantum Computation with One-Clean-Qubit Model as an Open Quantum System

arXiv:1902.03178 (2023) | Phys. Rev. A 107, 042222 | with Steve Campbell, John Goold, and André Xuereb

By studying the manipulation of classical and quantum information through a thermodynamic lens, this paper aims to understand what it means for a task to be complex and whether this corresponds to great thermodynamic work. The research was conducted in the contexts of quantum information compression and quantum algorithms.

time Currently working on :
- How thermodynamics limits our ability to correct errors in quantum computation.
- Hunting a trade-off between complexity and dissipation in quantum processes.
- Developing a framework within which we can model and estimate the thermodynamic cost of an agent acquiring knowledge of a quantum state in a given (see 6.) any basis.

Looking ahead :
I have become quite interested in the toolkit of the symmetric subspace developed in quantum information. It has been used to characterise the monogamy of entanglement, our ability to approximately clone and estimate quantum states as well as provide us the Quantum de Finetti Theorem. I am excited to try to use this toolkit to rederive ideas from the foundations of quantum thermodynamics and understand what it can teach us about the physics of many body systems.

I am also interested broadly interested in the role of knowledge in quantum physics. In classical thermodynamics the likelihood of a system being in a given microstate given your knowledge of the state of the system lies at the core of our thinking through Jayne's principle. With its effectiveness being clear from Landauer erasure and the resolution of the Maxwell Demon paradox. But in quantum physics, where classical knowledge plays such a pivotal role as a result of measurement -- we do not a have an understanding of the role of knowledge within in quantum theory itself. What states are harder to reconstruct than others and why? How does knowledge restrict our ability to carry out operations in resource theories? Answering these questions seems like it would be fun and satisfying.

Happy, thank you, more please. I am very very happy to be living the life of a quantum physicist, to be travelling the world talking to as many wonderful creative souls about as many interesting problems as possible.

Brain teasers:
- What's the most interesting and efficient way to estimate the integral of a real valued function through the evolution of a quantum system?