Workshop on Modern Trends in Quantum Theory

Session

Poster

25 May 2022, 15:30

Atrium

Description

Poster session

31. Applications of quantum computers in quantum chemistry

25/05/2022, 15:30

Poster

Quantum computing has received a lot of attention recently, and specifically its application in quantum chemistry looks very promising. This research project summarizes the most important methods used in calculating the electronic structure of a chemical system on quantum computers. This includes the formulation of the problem in first and second quantization and the use of classical...

42. Asymptotic synchronization and phase-locking in qubit networks

25/05/2022, 15:30

Poster

The work concerns asymptotic synchronization and phase-locking in qubit networks undergoing Markovian evolution described by the GKSL master equation with normal Lindblad operators. For a two-qubit system, all synchronization and phase-locking mechanisms within the given framework are obtained and classified, using solely analytic methods. In the case of synchronization, the results are...

39. Asymptotic trapping in coined Grover flip-flop quantum walks on general graphs with dynamical percolation

25/05/2022, 15:30

Poster

It is known from previous works that discrete flip-flop quantum walks with the Grover coin on finite graphs can exhibit the phenomenon of asymptotic trapping, where the walker can evade a sink introduced in the graph indefinitely with non-zero probability. This interference phenomenon is caused by so-called trapped states – eigenstates of the walk with limited support, i.e. with zero...

29. Benchmarking quantum computers using quantum state matching of qubits

25/05/2022, 15:30

Poster

We present our advances on the implementation of a measurement-induced nonlinear protocol for quantum state matching using some commercially available quantum computers. Using this implementation, we present a benchmark that detects quantitatively the device specific errors. In contrast to current benchmarks trends, our circuit is a non-random deep circuit. Among the devices analyzed, we...

34. Disorder-free localization in quantum walks

25/05/2022, 15:30

Poster

The localization phenomenon usually happens due to the existence of disorder in a medium. Nevertheless, specific quantum systems allow dynamical localization solely due to internal interactions. We study a discrete-time quantum walker which exhibits disorder-free localization. The quantum walker moves on a one-dimensional lattice and interacts with on-site spins by coherently rotating them...

37. Hearing the shape of a quantum boundary condition

25/05/2022, 15:30

Poster

We study the isospectrality problem for a free quantum particle confined in a ring with a junction. By characterizing the energy spectrum in terms of a spectral function, we classify all the possible self-adjoint realizations. The latter turn out to be divided in two classes, which are discerned by the action of parity.

Main reference: G. Angelone, P. Facchi and G. Marmo, *Hearing the...

41. Incremental Learning of Quantum Generative Adversarial Networks

25/05/2022, 15:30

Poster

Machine learning field has shown incredible impact on many kinds of optimization problems. Recently the power of machine learning was applied to speed up the quantum states preparation. Although approximation with quantum generative adversarial networks is one of the fastest ways to prepare a generic quantum state, training time for such models is still significant and can easily impair...

26. Measurement disturbance tradeoffs in three-qubit unsupervised quantum classification

25/05/2022, 15:30

Poster

We consider measurement disturbance tradeoffs in quantum machine learning protocols which seek to learn about quantum data. We study the simplest example of a binary classification task, in the unsupervised regime. Specifically, we investigate how a classification of two qubits, that can each be in one of two unknown states, affects our ability to perform a subsequent classification on three...

30. Nonlinear squeezing and its decoherence

25/05/2022, 15:30

Poster

Nonlinear squeezing is an important feature for universal quantum computing, that in principle enables universal control of a continuous variable system [1]. Simultaneously, it is a subject to current experimental effort [2,3,4]. We show its behaviour under decoherence and possibilities of protection by Gaussian operations [4]. Therefore, our results can enhance the ability to detect the...

32. On the steady and asymptotic subspaces of open quantum systems

25/05/2022, 15:30

Poster

The evolution of an open quantum system is described by a quantum channel, i.e. a completely positive trace-preserving map. Under the Markovian approximation, the continuous dynamics of an open quantum system is given by a semigroup with a Gorini-Kossakowski-Lindblad-Sudarshan (GKLS) generator. In this poster we will discuss several constraints for the number of steady and asymptotic states of...

38. Quantum estimation with driven quantum walk

25/05/2022, 15:30

Poster

Using quantum Fisher information (QFI), we will show that parameter estimation with a driven discrete-time quantum walk (QW) provides a better bound over the attainable precision when compared to standard QW. Here, we are studying the quantum estimation of the phase parameter of the evolution operator. With this study, we can also show that QW set-up can be used to reduce the variance in the...

36. Quantum graphs with preferred orientation coupling

25/05/2022, 15:30

Poster

In the presented poster, known results on the spectral properties of quantum graphs with preferred orientation coupling are reviewed. Special attention is paid to the recent result on magnetic ring chains with preferred orientation coupling.

25. Quantum local time

25/05/2022, 15:30

Poster

The trajectory of a quantum particle during unitary evolution between its preparation and a later measurement can not be studied without measuring the particle, but measurement disturbs the state and the statistics of the measurement outcomes no longer pertain to the original evolution. We show how using path integral methods a sensible quasi-probability can be assigned to the event of passing...

35. Quantum walk based state transfer algorithms on the complete $M$-partite graph

25/05/2022, 15:30

Poster

We introduce the general scheme of discrete-time quantum walk algorithm for the search and state transfer algorithm based on discrete-time quantum walk. We prove that adding a loop to each vertex improves success probability of the search algorithm on a complete $M$-partite graph in the limit of a large graph. We show that the state transfer algorithm performs perfect state transfer between...

40. Robust quantum search algorithm via non-unitary Zeno-like dynamics

25/05/2022, 15:30

Poster

We propose and analyze a non-unitary variant of the continuous time Grover search algorithm based on frequent Zeno-type measurements. We show that the algorithm scales similarly to the pure quantum version by deriving tight analytical lower bounds on its efficiency for arbitrary database sizes and measurement parameters. We study the behavior of the algorithm subject to noise, and find that...

22. Small angle asymptotics for Robin Laplacians on infinite circular cones

25/05/2022, 15:30

Poster

For $\varepsilon>0$ and $n\in\mathbb{N}$ consider the infinite cone $\Omega_{\varepsilon}:=\big\{(x_1,x')\in (0,\infty)\times\mathbb{R}^n: \, |x' | < \varepsilon x_1\big\}$ and the operator $Q_{\varepsilon}^{\alpha}$ acting as the Laplacian $u\mapsto-\Delta u$ on $\Omega_{\varepsilon}$ with the Robin boundary condition $\partial_\nu u=\alpha u$ at $\partial\Omega_\varepsilon$, where...