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Środowiskowe Seminarium z Informacji i Technologii Kwantowych

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do roku 2023/2024 Seminarium Kwantowa Informacja | kanał YouTube

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Zapraszamy do sali 0.06, ul. Pasteura 5 o godzinie 11:15

Kamil Korzekwa (PsiQuantum)

Quantum algorithms for nonlinear dynamics

The case for quantum computation rests on a simple idea: because Nature is fundamentally quantum mechanical, some physical systems should be more efficiently simulated by quantum computers than by classical ones. This expectation appears especially well founded in quantum chemistry, which is widely regarded as one of the most promising applications of future fault-tolerant quantum computers. However, some of the most consequential simulation problems arise not in quantum systems, but in classical dynamical systems such as fluids and plasmas. To what extent can quantum computers accelerate the simulation of such systems? The answer bears directly on the true scope of quantum advantage and, ultimately, on the breadth of quantum computing applications. In this talk, I will review the current evidence, discuss key open questions, and present ongoing work at PsiQuantum aimed at clarifying where quantum algorithms may offer meaningful improvements for the simulation of classical dynamics.

Zapraszamy do sali 0.06, ul. Pasteura 5 o godzinie 11:15

Jan Kołodyński (IFPAN)

Quantum information meets particle physics: Detecting entanglement in para-positronium annihilation photons

Zapraszamy do sali 0.06, ul. Pasteura 5 o godzinie 11:15

Stanisław Kurzyna (CENT QOT)

How Rydberg interactions allow to protect against the losses in microwave filed detection?

Zapraszamy do sali 0.06, ul. Pasteura 5 o godzinie 11:15

Mateusz Molenda (IFPAN)

Unlocking photodetection for quantum sensing with Bayesian likelihood-free methods and deep learning

To operate quantum sensors at their quantum limit in real time, it is crucial to identify efficient data inference tools for rapid parameter estimation. In photodetection, the key challenge is the fast interpretation of click-patterns that exhibit non-classical statistics---the very features responsible for the quantum enhancement of precision. We achieve this goal by comparingBayesian likelihood-free methods with ones based on deep learning (DL). While the former are more conceptually intuitive, the latter, once trained, provide significantly faster estimates with comparable precision and yield similar predictions of the associated errors, challenging a common misconception that DL lacks such capabilities. We first verify both approaches for an analytically tractable, yet multiparameter, scenario of a two-level system emitting uncorrelated photons. Our main result, however, is the application to a driven nonlinear optomechanical device emitting non-classical light with complex multiclick correlations; in this case, our methods are essential for fast inference and, hence, unlock the possibility of distinguishing different photon statistics in real time. Our results pave the way for dynamical control of quantum sensors that leverage non-classical effects in photodetection.

Zapraszamy do sali 0.06, ul. Pasteura 5 o godzinie 11:15

Gabriela Wójtowicz (University of Ulm)

Tensor network methods for quantum metrology

The quantum Fisher information (QFI) is a geometric measure of state deformation calculated along the trajectory parametrizing an ensemble of quantum states. It serves as a key concept in quantum metrology, where it is linked to the fundamental limit on the precision of the parameter that we estimate. However, the QFI is notoriously difficult to calculate due to its non-linear mathematical form. For mixed states, standard numerical procedures based on eigendecomposition quickly become impractical with increasing system size. To overcome this limitation, we introduce a numerical approach based on Lyapunov integrals that combines the concept of symmetric logarithmic derivative and tensor networks. In this talk I will present details of the numerical approach and discuss the advantages and limitations of our methodology through an illustrative example, where the thermal state of the transverse-field Ising model is used to estimate magnetic field amplitude.

[1] G. Wójtowicz, S. F. Huelga, M. M. Rams, M. B. Plenio, Phys. Rev. A 112, 052454 (2025) DOI: https://doi.org/10.1103/xjln-7ddy

Zapraszamy do sali 0.06, ul. Pasteura 5 o godzinie 11:15

Stanisław Sieniawski (IFT UW)

Adaptive quantum channel discrimination using methods of quantum metrology

Zapraszamy do sali 0.06, ul. Pasteura 5 o godzinie 11:15

Wojciech Górecki (Freie Universitat Berlin)

Protecting Heisenberg scaling in quantum metrology via engineered dressed states

Zapraszamy do sali 0.06, ul. Pasteura 5 o godzinie 11:15

Jacek Dziarmaga (Uniwersytet Jagieloński)

2D tensor networks for quantum simulations

I will make a brief introduction to tensor network (TN) states and algorithms that became a method of choice for strongly correlated quantum many body systems on a lattice in one and two dimensions. I will emphasize the 2D TN known as PEPS (pair-entangled projected state) and its two recent applications to unitary time evolution and thermal Gibbs states. One is the recent quantum computational advantage demonstration with the coherent D-Wave quantum annealer [1], where TN served, on the one hand, as a benchmark for the quantum simulator and, on the other hand, as the most competitive classical method that, nevertheless, in the end failed the competition with the quantum hardware. The other is tensor network simulation of finite temperature states in the Hubbard and t − J models – the two paradigmatic models of high-Tc superconductivity – that proved notoriously hard to solve analytically/numerically and, therefore, are subject to intensive experimental effort in the ultracold atoms community aiming at their quantum simulation. I will present some PEPS results [2,3] down to temperatures of one tenth of the hopping rate, in the pseudogap regime. These results, obtained directly in the thermodynamic limit, can serve as a guide/benchmark for the current experimental efforts. References

[1] A.D. King, A. Nocera, M.M. Rams, J. Dziarmaga,..., Science 388 (6743), 199
[2] A. Sinha, M.M. Rams, P. Czarnik, and J. Dziarmaga, Physical Review B 106 (19), 195105
[3] Y. Zhang, A. Sinha, M.M. Rams, J. Dziarmaga, Phys. Rev. B 113, 085113

Zapraszamy do sali 0.06, ul. Pasteura 5 o godzinie 11:15

Sławomir Sujecki (WAT, Instytut Systemów Łączności)

Implementation of QKD in Backbone DWDM Networks

Recently, increasing attention is given to an application of QKD in DWDM networks. In this contribution selected aspects of sending quantum signals through a DWDM network are discussed in the context of practical optical backbone telecom networks and modern cryptographic systems.

Zapraszamy do sali 0.06, ul. Pasteura 5 o godzinie 11:15

Andrzej Dragan (IFT UW)

Relativistic reason for quantum probability amplitudes

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