Mostra “Dire l’indicibile: L’entaglement quantistico”

La mostra divulgativa “Dire l’indicibile: l’entaglement quantistico” è una installazione di pannelli ed exibit interattivi, organizzata in occasione delle Italian Quantum Weeks.

Date di apertura: 14 – 21 aprile 2023

Luogo: Dipartimento di Fisica, Università degli Studi di Milano, via Celoria, 16 – Milano (Città Studi)

Orari di apertura:
Ven 14/4 9:00 – 13:00 13:30 – 17:30
Lun 17/4 9:00 – 13:00 13:30 – 17:30
Mar 18/4 9:00 – 13:00 13:30 – 17:30
Mer 19/4 9:00 – 13:00 13:30 – 17:30
Gio 20/4 9:00 – 13:00 13:30 – 17:30
Ven 21/4 9:00 – 13:00

Saranno disponibili visite guidate. La visita e la guida alla mostra sono gratuiti.
Le visite guidate per scuole superiori sono prenotabili a questo indirizzo

Scarica la locandina stampabile.

Seminar by Massimo Frigerio

We are happy to announce our next seminar.

Speaker: Massimo Frigerio (University of Milan, ITA)
When: Tuesday, 22nd Feb 2023, 11:30 PM (CET)
Where: Auletta QOpt – LITA 5th floor

Title: A dive into non-Gaussian quantum correlations

Seminar by Abolfazl Bayat

We are happy to announce our next seminar.

Speaker: Abolfazl Bayat (University of Electronic Science and Technology of China, Chengdu, China)
When: Wednesday 15th February 2023, 11:30 AM (CET)
Where: Aula Caldirola

Title: Quantum many-body sensors

Abstract: Ground state criticality of many-body systems is a resource for quantum enhanced sensing, namely Heisenberg precision limit, provided that one has access to the whole system. Indeed, for partially accessible probes the sensing capacity in the ground state reduces to the sub-Heisenberg limit. To compensate for this, we drive the system periodically and use the local steady state for quantum sensing. Remarkably, the steady state sensing shows a significant enhancement in its precision in comparison with the ground state and even shows super-Heisenberg scaling for a certain range of frequencies. The same setup can also be used for sensing AC fields. The precision in partially accessible systems may also be compensated through a sequence of measurements which are performed after a period of free evolution. We show that as the length of measurement sequence increases the precision surpasses the standard limit and asymptotically reaches Heisenberg scaling.
While most many-body quantum sensors achieve enhanced sensitivity within a very narrow region, known as local sensing, one may need a probe to measure an unknown parameter over a large interval. To address this issue, we formulate the notion of global sensing and establish a systematic method to optimize quantum many-body probes to achieve the best possible precision when the parameters of interest vary over arbitrarily large intervals.

[1] V. Montenegro, U. Mishra, A. Bayat, Phys. Rev. Lett. 126, 200501 (2021)
[2] U. Mishra, A. Bayat, Phys. Rev. Lett. 127, 080504 (2021)
[3] V. Montenegro, G. S. Jones, S. Bose, A. Bayat, Phys. Rev. Lett. 129, 120503 (2022)

Congratulations to Dr. Alessandro Candeloro!

Today (December 22nd 2022) Alessandro successfully defended his thesis Characterization and engineering of quantum systems for quantum technologies, thus obtaining his PhD degree from the University of Milan.

We congratulate with Alessandro for this important achievement in his research career and we wish him all the best for the future. Well done Alessandro!

Seminar by Giacomo Guarnieri

We are happy to announce our next seminar.

Speaker: Giacomo Guarnieri (Freie Universität Berlin)
When: Thursday, 15th December 2022, 9:30 AM (CET)
Where: Aula Caldirola

Title: Thermodynamics of Precision in quantum thermal machines: theory and experiment.

Abstract: Understanding and controlling microscopic quantum devices represents a major milestone. Their precision is related to the fluctuations of their measurable output, an aspect that becomes preponderant at the nano-scale. Achieving a regime where the machine operates at a given reliability/precision inevitably comes at a cost in terms of thermodynamic resources, such as dissipated heat or excess work, thus massively impacting the machines’ performances.
Thermodynamic Uncertainty Relations (TURs) have represented a landmark first step in understanding this balance, as they express a trade-off between precision, defined as the noise-to-signal ratio of a generic current, and the amount of associated entropy production. These results have deep consequences for quantum thermal machines, imposing an upper bound for their efficiency in terms of the power yield and its fluctuations. Such engines can be divided into two classes: steady-state heat engines and periodically driven heat engines. In this talk I will present and discuss the derivation of genuinely quantum corrections to TURs in both cases, which were obtained by combining techniques from quantum information theory and thermodynamics of geometry. Finally, I will report on an experimental measurement of such quantum correction in a trapped-ion experiment.

Seminar by Daniele Morrone

We are happy to announce our next seminar.

Speaker: Daniele Morrone (UniMi)
When: Thursday, 24th November 2022, 9:30 AM (CET)
Where: Aula Caldirola

Title: Charging a quantum battery in a non-Markovian environment: a collisional model approach

Abstract: We study the effect of non-Markovianity in the charging process of an open-system quantum battery. We employ collisional model framework, where the environment is described by a discrete set of ancillary systems and memory effects in the dynamics can be introduced by allowing these ancillas to interact. We focus on the case where this interaction is described by a partial-swap operator, and we consider both the discrete-time dynamics arising naturally from this model, and its continuous-time limit leading to a memory-kernel master equation under certain assumptions. We study in detail the behaviour of the steady-state ergotropy and the non-trivial interplay between the parameter controlling the information backflow of the environment and the other parameters characterizing the dynamics. Remarkably, we find that there is a maximum value of the ergotropyachievable: This value can be obtained either in the Markovian case, but only in the large-loss limit, as derived in [1], or in the presence of a non-Markovian environment also beyond the large-loss limit. In general, we show that the presence of environment with memory allows us to generate ergotropy near to its maximum value for a much larger region in the parameter space. Finally, we discuss in detail the role of non-Markovianity by evaluating the non-Markovianity measure for the different subsystems composing our quantum battery model. We remarkably find that the maximum value of ergotropy is in general obtained when the non-Markovianity for the battery subsystem only is close to zero, regardless the memory properties of the environment interacting with the charger.

[1] D. Farina, G. M. Andolina, A. Mari, M. Polini, and V. Giovannetti, Physical Review B 99, 035421 (2019), arXiv:1810.10890

Seminar by Giovanni Chesi

We are happy to announce our next seminar.

Speaker: Giovanni Chesi (INFN Pavia)
When: Thursday, 17th November 2022, 9:30 AM (CET)
Where: Aula Caldirola

Title: A general protocol for global multiphase estimation

Abstract: In principle, global estimation strategies allow to extract information on a phase or a set of phases without any prior knowledge about them. However, unlike the local estimation case, a global multiphase estimation strategy does not exist yet. We devised a protocol based on Holevo’s estimation theory that straightforwardly generalizes global single-phase estimation strategies to the multiphase scenario. We exploit our protocol to investigate the performance of multiphase global estimation. Moreover, we show that, in the single-phase case, our protocol generalizes at least two well-known estimation strategies, i.e. the Quantum Phase Estimation Algorithm and the optimal parallel-separable strategy.

Seminar by Matteo Rossi

We are happy to announce our next seminar.

Speaker: Matteo Rossi (University of Helsinki / Algorithmiq, FIN)
When: Thursday, 10th November 2022, 9:30 AM (CET)
Where: Aula Caldirola

Title: Informationally complete generalised quantum measurements for near-term quantum algorithms

Abstract: Today’s quantum computers are imperfect. They are made of dozens of qubits that can be prepared in highly non-classical states but, being very sensitive to noise, their ability to preserve quantum properties is very limited. This is why, despite the discovery of algorithms that in principle would allow us to simulate interesting and currently intractable problems in chemistry and materials, applications to relevant problems seem out-of-reach. In this talk I will present recently-introduced techniques that allow near-term quantum computers to run quantum algorithms that might potentially lead to quantum advantage soon. The underlying ingredient is the use of informationally complete generalised measurements (IC POVMs). Our results show how hybrid variational quantum-classical algorithms using IC data allow for noise attenuation, execution time reduction and efficient state preparation, paving the way to chemistry-related applications.

Seminar by Carlo Cepollaro

We are happy to announce our next seminar.

Speaker: Carlo Cepollaro (University of Vienna, AUT)
When: Thursday, 3rd November 2022, 9:30 AM (CET)
Where: Aula Caldirola

Title: Quantum reference frames: foundations and applications

Abstract: Every physical observation is made with respect to a frame of reference that is realized through a physical system. Ultimately, every physical system must obey quantum mechanics, so reference frames may show quantum properties. For this reason, Quantum Reference Frames (QRFs) [1] were introduced, along with a proposal of extension of the principle of covariance of physical laws to all QRFs. I will describe the main ideas that have been discussed in the literature and give some physical examples. I will also talk about one of the main applications of QRFs, namely a Quantum extension of the Einstein’s Equivalence Principle [2], and the proposal of an experimental test for this principle [3].

[1] F. Giacomini, E. Castro-Ruiz, C. Brukner, Quantum mechanics and the covariance of physical laws in quantum reference frames. Nat Commun 10, 494 (2019).
[2] F. Giacomini, C. Brukner, Einstein’s Equivalence principle for superpositions of gravitational fields and quantum reference frames, arXiv:2012.13754.
[3] CC, F. Giacomini, Quantum generalisation of Einstein’s Equivalence Principle can be verified with entangled clocks as quantum reference frames, arXiv:2112:03303.

Seminar by Michele Notarnicola

We are happy to announce our next seminar.

Speaker: Michele Notarnicola (University of Milan, ITA)
When: Thursday, 27th October 2022, 9:30 AM (CEST)
Where: Auletta QOpt – LITA 5th floor

Title: Phase-sensitive amplification for quantum loss-tolerant measurements

Abstract: Homodyne measurement is a corner-stone method of quantum optics that measures the quadratures of light, i.e. the quantum optical analog of the canonical position and momentum. However, standard homodyne is fragile to detection losses, especially in the presence of non-classical states of radiation. We propose a robust method to implement homodyne detection that is loss-tolerant, by employing optical parametric amplification to reconstruct quadrature distributions from photon-number distributions measured via direct detection. As a proof of principle, we have employed this parametric homodyne detection (PHD) setup to Wigner function tomography of a multi-mode squeezed vacuum state. The obtained Wigner function has shown a squeezing of −7.5 ± 0.4 dB and a purity of 0.91 ± 0.09 despite more than 90% detection losses. This method is suitable for the tomography of spatially and temporally multimode quantum states, proving it to be a powerful tool for optical quantum information.

Quantum Technology Lab – Dipartimento di Fisica – Università degli Studi di Milano