Dariusz KajtochIndependent Researcher
Dariusz Kajtoch
Doctor of Philosophy
About
17
Publications
9,097
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138
Citations
Introduction
Skilled Theoretical Quantum Physicist with 3+ year experience in international environment. I specialized in quantum metrology and ultra-cold quantum gases. Currently outside academia, working as Research Engineer in Natual Language Processing.
Skills and Expertise
Additional affiliations
October 2015 - June 2018
Publications
Publications (17)
Novel intent discovery automates the process of grouping similar messages (questions) to identify previously unknown intents. However, current research focuses on publicly available datasets which have only the question field and significantly differ from real-life datasets. This paper proposes methods to improve the intent discovery pipeline deplo...
We introduce a new benchmark for assessing the quality of text-to-text models for Polish. The benchmark consists of diverse tasks and datasets: KLEJ benchmark adapted for text-to-text, en-pl translation, summarization, and question answering. In particular, since summarization and question answering lack benchmark datasets for the Polish language,...
Implementation of the quantum interferometry concept to spin-1 atomic Bose–Einstein condensates is analyzed by employing a polar state evolved in time. In order to identify the best interferometric configurations, the quantum Fisher information (QFI) is maximized. Three optimal configurations are identified, among which one was not reported in the...
Implementation of the quantum interferometry concept to spin-1 atomic Bose-Einstein condensates is analyzed by employing a polar state evolved in time. In order to identify the best interferometric configurations, the quantum Fisher information is maximized. Three optimal configurations are identified, among which one was not reported in the litera...
This thesis focuses on theoretical schemes concerning the preparation and characterization of both squeezed and entangled quantum states in the spinor Bose-Einstein condensate with a total spin F = 1. The subject matter of the study covers two issues, discussed in the publications [1,2], and it also provides more insights into the topic. In the fir...
Using the time-dependent Bogoliubov approach, we study adiabaticity for a two-component Bose-Einstein condensate in a 3D time-dependent optical lattice with unit filling, in the superfluid and weakly interacting regime. We show that raising the lattice potential height can couple the ground state of the Bogoliubov Hamiltonian to excited states with...
We consider general three-mode interferometers using a spin-1 atomic Bose-Einstein condensate with macroscopic magnetization. We show that these interferometers, combined with the measurement of the number of particles in each output port, provide an ultra-high phase sensitivity. We construct effective two-mode interferometers which involve two Zee...
We propose a method to obtain a regular arrangement of two-level atoms in a three-dimensional optical lattice with unit filling, where all the atoms share internal state coherence and metrologically useful quantum correlations. Such a spin-squeezed atomic crystal is obtained by adiabatically raising an optical lattice in an interating two-component...
We study theoretically usability of spin-1 Bose condensates with nonzero magnetization in a homogeneous magnetic field for quantum metrology. We demonstrate Heisenberg scaling of the quantum Fisher information for states in thermal equilibrium, including the zero temperature case. It applies to both antiferromagnetic and ferromagnetic interactions....
We analyze a scheme for storage of entanglement quantified by the quantum
Fisher information in the two-axis countertwisting model. A characteristic
feature of the two-axis countertwisting Hamiltonian is the existence of the
four stable center and two unstable saddle fixed points in the mean-field phase
portrait. The entangled state is generated dy...
We study the effect of dipolar interactions on the level of squeezing in
spin-1 Bose-Einstein condensates by using the single mode approximation. We
limit our consideration to the $\mathfrak{su}(2)$ Lie subalgebra spanned by
spin operators. The biaxial nature of dipolar interactions allows for dynamical
generation of spin-squeezed states in the sys...
We present the theory of quantum evolution and dynamical generation of entangled states in a two-mode Bose-Einstein condensate. We show that the interactions between constituent particles are essential to entangle the initial coherent state. We quantify all the useful states for the high precision quantum interferometry by the spin squeezing parame...
We study the quantum dynamics generated by a two-axis counter-twisting
Hamiltonian from an initial spin coherent state in a spin-$1/2$ ensemble. A
characteristic feature of the two-axis counter-twisting Hamiltonian is the
existence of four neutrally stable and two saddle unstable fixed points. The
presence of the last one is responsible for a high...
Questions
Questions (7)
All the research papers I found so far, are just showing measurement of the squeezing parameter or quantum Fisher Information (QFI). Of course authors mention that, due to large QFI or strong squeezing this setup can be used for metrological purposes beyond standard quantum limit (SQL). I could not find any papers, which actually perform estimation of the unknown phase and show that the precision is beyond SQL. I am curious from the point of view of estimation in the presence of decoherence (which is always present). Theoretical papers indicate that entangled states are basically useless if frequency is estimated (e.q. Ramsey spectroscopy).
I need to determine numerically the ground state energy of the Fermi-Hubbard model when total filling is n=1, but the number of fermions with spin up: 'n_up', and spin down: 'n_down' can take any value (but of course n_up + n_down = 1).
Do you know of any C++/Fortran/Python etc. ready to use package that would allow me to determine ground state energy for different hopings 'J', interaction energies 'U' and compositions n_up, n_down?
I would like to know if the energy gap between ground state and the first excited state in a Bose-Hubbard model have been determined? In particular I would like to know how does it scale with the system size? So far I couldn't find any numerical data for 1D, 2D or 3D.
What are the challenges people face while developing such an atomic clock? What is the dominant source of error? Clock lasers? Dick effect?
Atom losses in ultracold gases depend on the n-body correlation function. For example three-body losses depend on the three-particle correlation function. Let's assume I load BEC into an optical lattice and I change depth if the lattice. I would expect different loss rate when I am in the Mott insulator state, close to the phase transition or in the superfluid regime. Are there any papers that analyzed this behavior? Or am I completely wrong and the loss rate can not be manipulated with lattice depth?
I am interested in studying dynamics of two-component BEC using rubidium-87 or sodium-23. For this purpose I need information about s-wave scattering lengths and two-body losses.
Information about scattering lengths and two-body loss coefficients for |F=1, mf=-1> and |F=2, mf=1> are well known, but I was thinking also about other combinations. In particular:
|F=1, mf=-1> and |F=2, mf=2>
What kind of experimental/theoretical data are available for different combination of states |F=1, mf=i>, |F=2, mf=j>? I am interested in s-wave scattering lengths: aii, ajj, aij and two-body loss coefficients: gij and gjj
Strontium-88 and Ytterbium-174 are bosonic isotopes with clock transition between singlet and triplet states: 1S0 - 3P0. Do you know of a paper where s-wave scattering lengths for collisions between singlet-singlet, triplet-triplet and singlet-triplet states are measured?
