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# Instytut Fizyki Teoretycznej

Wydział Fizyki, Astronomii i Informatyki Stosowanej Uniwersytet Jagielloński

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## Sukcesy pracowników IFT (2022)

### komentarz Jakuba Zakrzewskiego w News and Views, Nature Physics

Experiment reaches the stage of testing many body localization in well controlled experiments. Two such set-ups reported their results on interacting kicked rotors in Nature Physics. Kicked rotor is a paradygmatic model for quantum chaos - will interacting rotors play a similar role in many body physics?

Picture shows delocalization in a many-body quantum kicked rotor. Evolution of the momentum (k) distribution of a gas of interacting atoms in time under a kicking with period T. The system starts from a highly localized state represented by a strongly prominent central peak. Localization persists until the effect of interactions manifests in the broadening of the peak, ultimately resulting in complete delocalization as the number of kicks increases.

Read the commentary in Nature Physics.

### Romuald A. Janik, Matti Järvinen, Hesam Soltanpanahi, and Jacob Sonnenschein; publikacja w Physical Review Letters; publikacja w Physical Review Letters

Bubble wall velocities in first order phase transitions is a topic of broad relevance, especially in view of applications to the early universe and production of gravitational waves. Conventionally, the determination of such velocities is thought to require the computation of friction, a complex non-equilibrium problem. In this article, we showed that for a range of strongly coupled theories having holographic duals, the physics is much simpler: the velocity can be expressed in terms of a perfect fluid hydrodynamic formula, and thus in terms of the equation of state in a compact form. Namely, it is given by: $v_\mathrm{domain\ wall} = \tanh \int_{p_{c}}^{p_A} \frac{dp}{(\epsilon + p)c_s} \ \equiv\ \tanh \int_{T_{c}}^{T_A} \frac{dT}{T c_s}$, where $p_C$ is the critical pressure and $p_A$ is the pressure of the high entropy phase.

Phys. Rev. Lett. 129, 081601 (2022)

### Grant Maestro 13 dla Krzysztofa Sachy

• Projekt "Czaso-tronika" prof. Krzysztofa Sachy otrzymał finansowanie w ramach grantu Maestro 13 Narodowego Centrum Nauki, więcej informacji pod tym linkiem.

### Kamil Korzekwa i Matteo Lostaglio; publikacje w Physical Review A i Physical Review Letters wybrane jako Editor's Suggestion i opisane w Physics Viewpoint

By combining continuous and discrete theoretical approaches, researchers show how to plot an optimal path from one non-equilibrium quantum state to another.

With the rapid progress in experimental control of quantum systems, we are experiencing miniaturization of heat engines, pumps and refrigerators all the way to the quantum realm, where the operation of these devices depends on a fine-tuned control of their interactions with a macroscopic thermal environment. A central problem in this setting is to find optimal interaction schedules that maximize a desired objective function, such as the efficiency of a quantum heat engine or the cooling power of a quantum refrigerator. In their works, the authors address this pressing issue by presenting a novel algorithmic approach that can solve such complex optimization problems in out-of-equilibrium setups and returns explicit elementary controls realizing optimal transformations. The framework allows one to access regimes where alternative numerical or analytical approaches are unfeasible, and it paves the way to an algorithmic approach to the development of quantum thermodynamic protocols. The usefulness of this perspective is illustrated with examples from cooling, work extraction, catalysis and the assessment of the role of memory effects in biological systems.

Phys. Rev. Lett. 129, 040602 (2022)

Phys. Rev. A 106, 012426 (2022)

Coverage in Physics Viewpoint: Physics 15, 110 (2022)

### Granty NCN dla badaczy z IFT

• dr Marcin Zagórski – Zrozumienie biofizycznych czynników ograniczających precyzję powstawania wzoru w trakcie rozwoju tkanki
• dr Mario Rainer Flory – Holograficzne powiązania między polami kwantowymi, informacją a grawitacją
• dr Chunshan Lin – Nowa fizyka w świetle pierwotnych reliktów z wczesnego Wszechświata

### Titas Chanda, Maciej Lewenstein, Jakub Zakrzewski oraz Luca Tagliacozzo; publikacja w Physical Review Letters

The Higgs mechanism is an essential ingredient of the Standard Model of particle physics that explains the ‘mass generation’ of gauge bosons. In three spatial dimensions, a spontaneous breaking of symmetry triggers the Abelian-Higgs mechanism in the system while in one spatial dimension the phase diagram onsists of a single confined phase only. Due to this boring expectation of a single phase in the continuum field theory, the Abelian-Higgs model has never been explored in 1+1 dimensional discrete lattice before. We fill this gap.

Unlike the system in continuum, two distinct regions in the lattice version are identified, namely the confined and Higgs regions. These two regions are separated by a line of first order phase transitions that ends in a second order critical point. Above this critical point these two regions are smoothly connected by a crossover. The presence of a second order critical point allows one to construct an unorthodox continuum limit of the theory that is described by a conformal field theory. (CFT).

Phys. Rev. Lett. 128, 090601 (2022)

### Suhail Ahmad Rather, Adam Burchardt, Wojciech Bruzda, Grzegorz Rajchel-Mieldzioć, Arul Lakshminarayan oraz Karol Życzkowski; publikacja w Physical Review Letters

In the paper we present analytical solution to the quantum analogue of the famous problem of 36 officers of Euler. Classically impossible puzzle turns out to be solvable in the quantum realm. The result gives a positive answer to several related questions concerning existence of a pair of quantum orthogonal Latin squares of size six, Absolutely Maximally Entangled state AME(4, 6) for four parties with six levels each, unitary matrix of size 36 with a very particular internal structure, and special classes of tensors with four indices each running from 1 to 6. Moreover, this can open new possibilities in the theory of Quantum Error Correcting Codes.

The attached picture contains four dice. If they were quantum, when rolled, the outcomes of any two would be strictly correlated with the outcomes for the other two. This roughly explains the idea behind the new AME state the existence of which has been questioned for years.

Phys. Rev. Lett. 128, 080507 (2022)

### Michał Eckstein stypendystą MEiN

Dr Michał Eckstein związany z Jagiellonian Quantum Information Team otrzymał stypendium MEiN dla wybitnych młodych naukowców.

### Hossein Taheri, Andrey B. Matsko, Lute Maleki oraz Krzysztof Sacha; publikacja w Nature Communications

In the publication in Nature Communications, an optical platform is described in which dissipative discrete time crystalline behavior is demonstrated in the laboratory.

The experiments constitute a milestone towards chip-scale discrete time crystals, paving the way from complex labs toward real-world applications. The heart of these experiments is a tiny optical cavity (solid disc-shaped resonator of ≈1 mm diameter) pumped by two diode lasers without any need for highly complex and expensive laboratory equipment.

Discrete time crystals realized experimentally so far have been "small" crystals in the time dimension (i.e., evolving with a period twice or three times as long as the period of the external drive). In the work published in Nature Communications it is demonstrated that “big” dissipative discrete time crystals are attainable in the laboratory. Big discrete time crystals open new horizons for condensed matter research in the time domain. In the published paper, the formation of defects in discrete time crystals are described. That is, the formation of the temporal counterpart of solid-state crystals with point defects like vacancies and interstitials.

Wywiad z autorami w Physics World.

Nat. Commun. 13, 848 (2022)