Joint Seminar on Quantum Information and Technologies
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until 2023/2024 Quantum Information Seminar
2022-09-20 (Tuesday)
join us at 11:15 
Eliska Greplova (Delft University of Technology)Machine Learning and Large Scale Quantum Devices - CANCELLED!!!
The seminar is cancelled!!!
2022-06-09 (Thursday)
join us at 11:15
Giovanni Di Fresco (Università di Palermo)Can compatibility in multi-parameter estimation schemes be induced by criticality?
The Seminar will be ONLINE ONLY using ZOOM under the following link: https://zoom.us/j/92894130767 (Passcode: R6Vx6E).
It is known that many-body systems near a quantum phase transition (QPT) exhibit severalproperties which makes them appealing for metrological purposes. Indeed, it is now wellestablished and widely used that the divergences of the quantum Fisher informationobserved near a QPT can be used to increase the precision in the estimation of a parameter.Meanwhile, when it comes to the simultaneous estimation of multiple parameters, thebenefits of criticality are much harder to analyze due to possible incompatibilities arising fromthe Heisenberg uncertainty. This involves the use of quite convoluted quantities, as theHolevo-Cramer-Rao bound, which are far from straightforward to evaluate in systems ofinterest. Here we study the quantumness (R), a scalar index, which provides an asymptoticbound on the compatibility of a metrological scheme. The advantage of this approach is thatR can be easily evaluated once the Quantum Fisher information and the mean Uhmlanncurvature are known. Moreover, a scaling analysis of R reveals that many-body criticalitiesgenerally improve the compatibility in a multi-parameter framework. In fact, we show thatthe quantum critical point is a good place to look for compatibility. We corroborate thesegeneral statements with numerical simulations performed on some representative systems,such as Ising chain and XY chain, in which we find this positive criticality effects
It is known that many-body systems near a quantum phase transition (QPT) exhibit severalproperties which makes them appealing for metrological purposes. Indeed, it is now wellestablished and widely used that the divergences of the quantum Fisher informationobserved near a QPT can be used to increase the precision in the estimation of a parameter.Meanwhile, when it comes to the simultaneous estimation of multiple parameters, thebenefits of criticality are much harder to analyze due to possible incompatibilities arising fromthe Heisenberg uncertainty. This involves the use of quite convoluted quantities, as theHolevo-Cramer-Rao bound, which are far from straightforward to evaluate in systems ofinterest. Here we study the quantumness (R), a scalar index, which provides an asymptoticbound on the compatibility of a metrological scheme. The advantage of this approach is thatR can be easily evaluated once the Quantum Fisher information and the mean Uhmlanncurvature are known. Moreover, a scaling analysis of R reveals that many-body criticalitiesgenerally improve the compatibility in a multi-parameter framework. In fact, we show thatthe quantum critical point is a good place to look for compatibility. We corroborate thesegeneral statements with numerical simulations performed on some representative systems,such as Ising chain and XY chain, in which we find this positive criticality effects
2022-06-02 (Thursday)
room 1.02, Pasteura 5 at 11:15
Bartosz Regula (University of Tokyo)No second law of entanglement manipulation after all
Many fruitful analogies have emerged between the theories of quantum entanglement and thermodynamics, motivating the pursuit of an axiomatic description of entanglement akin to the laws of thermodynamics. A long-standing open problem has been to establish a true second law of entanglement, and in particular a unique function which governs all transformations between entangled systems, mirroring the role of entropy in thermodynamics. Contrary to previous promising evidence, here we show that this is impossible, and no direct counterpart to the second law of thermodynamics can be established. This is accomplished by demonstrating the irreversibility of entanglement theory from first principles — assuming only the most general microscopic physical constraints of entanglement manipulation, we show that entanglement theory is irreversible under all non-entangling transformations. We furthermore rule out reversibility without significant entanglement expenditure, showing that reversible entanglement transformations require the generation of macroscopically large amounts of entanglement according to certain measures. Our results not only reveal fundamental differences between quantum entanglement transformations and thermodynamic processes, but also showcase a unique property of entanglement which distinguishes it from other known quantum resources. (arXiv:2111.02438)
The Seminar will take a HYBRID form. It will take place in room 1.02 but will be simmultaneously tranmitted via ZOOM under the following link: https://zoom.us/j/92894130767 (Passcode: R6Vx6E).
The Seminar will take a HYBRID form. It will take place in room 1.02 but will be simmultaneously tranmitted via ZOOM under the following link: https://zoom.us/j/92894130767 (Passcode: R6Vx6E).
2022-05-19 (Thursday)
room 1.02, Pasteura 5 at 11:15
Marco Fellous Asiani (QOT CENT UW)Minimizing the energetic cost of large-scale quantum computers
Despite its societal and industrial relevance, how energy consumption will impact the scalability of quantum computers remains a scarcely explored question. Properly addressing it mandates synergies between fundamental research and enabling technologies, the former (resp. the latter) managing the computing performances (resp. the macroscopic resource consumption). This effort requires to set up common methodologies and languages. Here we propose such methodology and apply it to the case of a superconducting fault-tolerant quantum computer. Based on a comprehensive modeling, we study the impact of various parameters on the global power consumption, ranging from the software (quantum error correction code, quantum algorithms) to the hardware (quality of qubits) and engineering parameters (cryogeny, controlling electronics, wiring). Our goal is to provide a unified "full-stack" picture allowing to enhance the energetic scalability of quantum computers. We use our framework to provide realistic estimations of the minimal energetic bill for fault-tolerant quantum computations. In particular, we estimate the minimum energy required to break RSA 2048 on a fault-tolerant quantum computer based on concatenated error correction. Our methodology is general and extendable to other qubits, codes and quantum technologies. Finally, we exhibit some fundamental differences between how (and why) energy is used in quantum computers compared to classical computers.
The Seminar will take a HYBRID form. It will take place in room 1.02 but will be simmultaneously tranmitted via ZOOM under the following link: https://zoom.us/j/92894130767 (Passcode: R6Vx6E).
The Seminar will take a HYBRID form. It will take place in room 1.02 but will be simmultaneously tranmitted via ZOOM under the following link: https://zoom.us/j/92894130767 (Passcode: R6Vx6E).
2022-05-12 (Thursday)
room 1.02, Pasteura 5 at 11:15
Stanisław Kurdziałek (IFT UW)Measurement susceptibility in quantum estimation
The Seminar will take a HYBRID form. It will take place in room 1.02 but will be simmultaneously tranmitted via ZOOM under the following link: https://zoom.us/j/92894130767 (Passcode: R6Vx6E).
2022-04-28 (Thursday)
room 1.03, Pasteura 5 at 11:15
Rafal Demkowicz-Dobrzanski (IFT UW)Coherence and Decoherence in Quantum Metrology - the expected and the unexpected
The Seminar will take a HYBRID form. It will take place in room 1.02 but will be simmultaneously tranmitted via ZOOM under the following link: https://zoom.us/j/92894130767 (Passcode: R6Vx6E).
Still, since the seminar will be done on the blackboard the ONSITE presence is encouraged!
Still, since the seminar will be done on the blackboard the ONSITE presence is encouraged!
2022-04-21 (Thursday)
room 1.03, Pasteura 5 at 11:15
Seminar Cancelled!!!
2022-04-07 (Thursday)
room 1.02, Pasteura 5 at 11:15
Emil Zeuthen (Niels Bohr Institute, University of Copenhagen)Trajectories without quantum uncertainties in composite systems with disparate energy spectra
The Seminar will take a HYBRID form. It will take place in room 1.02 but will be simmultaneously tranmitted via ZOOM under the following link: https://zoom.us/j/92894130767 (Passcode: R6Vx6E)
2022-03-31 (Thursday)
room 1.02, Pasteura 5 at 11:15
Alexander Streltsov (QOT CENT UW)Entanglement catalysis for quantum states and noisy channels
The Seminar will take a HYBRID form. It will take place in room 1.02 but will be simmultaneously tranmitted via ZOOM under the following link: https://zoom.us/j/92894130767 (Passcode: R6Vx6E)
2022-03-24 (Thursday)
room 1.02, Pasteura 5 at 11:15
Jochen Schroeder (Chalmers University of Technology, Sweden)Ultra-sensitive coherent detection for space communications
Optical communication is being considered by all major spaceagencies to complement current microwave technology. In thispresentation I will review our work on using phase-sensitive amplifiersfor improving receiver sensitivity and discuss multi-aperture combiningtechniques working at very low optical powers
The Seminar will take a HYBRID form. It will take place in room 1.02 but will be simmultaneously tranmitted via ZOOM under the following link: https://zoom.us/j/92894130767 (Passcode: R6Vx6E)
The Seminar will take a HYBRID form. It will take place in room 1.02 but will be simmultaneously tranmitted via ZOOM under the following link: https://zoom.us/j/92894130767 (Passcode: R6Vx6E)