##### CUMBERLAND LODGE 2019

##### QUANTUM Physics: The Second Revolution

##### AbOUT

Maxwell’s Society longest running event is back for its 68th annual conference! Over the past decades, the Society has organized a study weekend on an annual basis at the Cumberland Lodge, located in the heart of the Great Park of Windsor. The goal of this event: to inspire and introduce our members to cutting-edge research on a focused topic. This year, the event runs from the 1st to the 3rd of March, with Quantum Information on the menu, in all its strangeness!

Since this is our long-awaited event, we hope for everyone’s best conduct. It is never too early to stand professionally in the research world, with a beautiful chance to discover the limits of knowledge.

Cumberland Lodge is a formal Royal residence set in the heart of Windsor Great Park and has been the home of an educational foundation since 1947. With a games room for playing, fields and nature for wandering, and skies for stargazing; this is an academic event with social aspects to not underestimate. We are looking forward to seeing you there!

Further details will be announced soon.

##### SPEAKERS

## Dr James Millen

## (KCL)

## Dr Janet Anders

## (Exeter)

## Alexander franklin

## (KCL)

## Dr MATTY HOBAN

## (Goldsmith university)

## Dr YING LIA LI

## (UCL)

## alexander franklin

## (kCL)

##### IMpressions

##### ABSTRACTS

Why isn’t the world more weird?

- DR JAMES MILLEN

Quantum physics makes some astounding predictions: superposition, entanglement, and teleportation to name just three. These are experimentally proven using atoms and photons, to an exceptional degree of accuracy. We also know that Nature offers us one of two evils. Either, particles do not have defined properties until a measurement is performed (a “lack of realism”), or information can travel arbitrary distances in an arbitrarily short time (“non-locality”).

So far, so weird. If this is true, then why doesn’t the world around us seem more strange? In this talk I will explore the concept of decoherence, which explains why it is difficult to observe quantum phenomena on our scale. I will present the experimental techniques that people use to probe at the edges of quantum physics, to see if at some point it just… stops, and what might cause this. Finally, we will discuss what it means for all of us if there is no breaking point, and whether we could ever put a living thing into a quantum state.

Quantum Thermodynamics and Information at the nanoscale

- DR JANET ANDERS

Thermodynamic laws have been key for the design of useful everyday devices from car engines to solar cells. Technology’s continuing miniaturisation to the nanoscale is expected to soon enter regimes where standard thermodynamic laws do not apply. I will briefly introduce quantum thermodynamics, an emerging research field that aims to uncover the thermodynamic laws that govern small systems that can also host quantum properties [1].

I will explain the classical paradox of Maxwell’s demon, who is able to extract work from a system in contact with a single heat-bath, which violates the second law of thermodynamics. The resolution of this paradox required the insight that an intimate relationship exists between information and thermodynamics, a relation today known as Landauer’s erasure principle, or “information is physical”. I will describe the first realisation of a quantum Maxwell demon [2], where the demon is a microwave cavity that encodes quantum information about a superconducting qubit. One confirms that the paradox is only resolved by taking the demon’s memory into account. [2]

Finally, I will describe a new quantum information process that mirrors Landauer’s erasure. I will show that when implementing this process, it is possible to extract work from quantum coherence [3], which has no analogue in classical thermodynamics. The findings uncover a new perspective on the role of coherence in thermodynamics, and point us on the path to developing quantum information machines.

[1] Quantum thermodynamics, S. Vinjanampathy, J. Anders, Contemporary Physics 57, 545 (2016).

[2] Observing a quantum Maxwell demon at work, N. Cottet, et al, PNAS 114, 7561 (2017).

[3] Coherence and measurement in quantum thermodynamics, P. Kammerlander, J. Anders, Scientific

Reports 6, 22174 (2016).

THE INVASION OF THE QUANTUM COMPUTER

- DR MATTY HOBAN

The fields of machine learning and artificial intelligence have emerged by combining techniques from probability theory and computer science. Importantly, it uses classical probability theory and classical computer science. Quantum theory can be seen as a different kind of probability theory: it makes statistic predictions given systems that have counter-intuitive properties such as entanglement. Not only quantum probabilities, we could have quantum computers, which are computers that utilise these same counterintuitive properties to speed up calculations. So what happens to machine learning when we combine quantum probability theory with quantum computer science? I will discuss not only how we could use quantum computers to solve problems in machine learning, but also how techniques from artificial intelligence and machine learning can be used to better understand quantum theory.

jack of all trades: how to commercialise quantum technology

- DR ying lia li

There has been significant investment from industry and governments to bring forth quantum technologies to the commercial market. This so-called ‘second quantum revolution’ aims to exploit recent advancements in our ability to detect, manipulate and simulate quantum objects for both software and hardware applications. In this talk I will describe the commercial appetite for quantum technology and how this can potentially transform society through the discovery of new drugs, ultraprecision quantum sensing, and surpassing the best classical supercomputers. I will discuss the successes of the UK National Quantum

Technologies Programme including lessons that can be learnt from this £270 million government initiative.

Using examples from my own experience taking an experiment from lab to outdoor field-trial, I will explain why multidisciplinary skills are crucial for commercialising quantum technology and how being a ‘jack of all trades’ has allowed me to start a quantum spin-out company.

the physics and philosophy of quantum collapse

- Mr alexander franklin

Although quantum mechanics is wildly successful, the measurement problem remains unresolved: how come the quantum wavefunction appears to be governed by certain (unitary) dynamics most of the time and different (collapse) dynamics during measurement?

The predictive success of quantum theory requires that quantum superpositions are sometimes interpreted probabilistically, and sometimes as true features of the quantum state, but there is no accepted and precise way of choosing when to apply these incompatible views. The suggestion that quantum collapse is a real, physical process offers one solution to this problem. It’s appealing insofar as it offers new physics, which should be experimentally testable. In this talk, I’ll set out the measurement problem in more detail, discuss some recent theoretical and philosophical developments of how we think about collapse, and suggest how these might be ruled in or out experimentally.

##### Cumberland lodge archive

Find out about previous Cumberland Lodge weekends here.