Seminars 2021

This series of informative seminars on quantum technologies has the goal of providing an introduction on the hottest topics in the field. The targeted audience includes students and non expert researchers.

Those who are interested to attend to the seminars are invited to subscribe the mailing list to receive the links to the video conference. Contacts: Angelo Nucciotti, Andrea Giachero


Anna Grassellino

Superconducting Quantum Materials and Systems (SQMS) – a new DOE National Quantum Information Science Research Center

Anna Grassellino (Fermilab, USA)

Wednesday February 24, 2021, 17:00 CEST

indico with abstract, slides, and video

Quantum Communications in Space enabling new tests of Quantum Mechanics and secure communications

Paolo Villoresi
(Università di Padova - DEI / INFN - Sez. di Padova, Italia)

Friday 9 April 2021 17:00 CEST

Paolo Villoresi

Abstract and material

Quantum Communications are based on the sharing of quantum states of light over long distances, and are of interest to address the interplay of Quantum Physics and Gravity as well as the applications as quantum key distribution on very long scales.  The QC experiments along Space channels were realized at MLRO - Matera Laser Ranging Observatory of the ASI Italian Space Agency, in Matera, Italy.

slides - video recording

David Pappas

Fabrication of superconducting circuits and universal gate set for strongly ZZ-coupled superconducting qubits

David Pappas (NIST, Boulder, USA)

April 19, 2021 - 17:00 CEST

Abstract and material

High-fidelity single- and two-qubit gates are essential building blocks for a fault-tolerant quantum computer. While there has been much progress in suppressing single-qubit gate errors in superconducting qubit systems, two-qubit gates still suffer from error rates that are orders of magnitude higher. 

One limiting factor is the residual ZZ-interaction, which originates from a coupling between computational states and higher-energy states. While this interaction is usually viewed as a nuisance, here we experimentally demonstrate that it can be exploited to produce a universal set of fast single- and two-qubit entangling gates in a coupled transmon qubit system. 

To implement arbitrary single-qubit rotations, we design a new protocol called the two-axis gate that is based on a three-part composite pulse. It rotates a single qubit independently of the state of the other qubit despite the strong ZZ-coupling. 

We achieve single-qubit gate fidelities as high as 99.1% from randomized benchmarking measurements. We then demonstrate both a CZ gate and a CNOT gate. Because the system has a strong ZZ-interaction, a CZ gate can be achieved by letting the system freely evolve for a gate time tg=53.8ns. To design the CNOT gate, we utilize an analytical microwave pulse shape based on the SWIPHT protocol for realizing fast, low-leakage gates. We obtain fidelities of 94.6% and 97.8% for the CNOT and CZ gates respectively from quantum progress tomography. 

slides - video recording

Information is physical: dalle diseguaglianze di Bell alle tecnologie quantistiche

Matteo Paris (Università di Milano, Italia)

May 3, 2021 - 17:00 CEST

Abstract and material

Trasmettere o manipolare informazione implica la codifica sui gradi di liberta di un sistema fisico. Di fatto, le caratteristiche quantistiche dei sistemi fisici influenzano pesantemente le loro proprieta di trasmissione, manipolazione, stoccaggio e lettura dell'informazione, sia introducendo fonti di rumore ineliminabile, sia offrendo nuovi gradi di liberta che possono migliorare le prestazioni.

In questo seminario verranno illustrati alcuni concetti fondamentali ed protocolli per la comunicazione ed il calcolo dove le caratteristiche quantistiche giocano un ruolo rilevante. In particolare si sottolineerà il ruolo dell'entanglement come risorsa per il trattamento quantistico dell'informazione.

Verranno inoltre illustrati alcuni problemi aperti ed i temi attuali della ricerca in informazione quantistica.

slides - video recording


Impact of ionizing radiation on superconducting qubit coherence

Joe Formaggio (MIT, Boston, USA)

May 17, 2021 - 17:00 CEST

Abstract and material

Over the past few years, there has been a growing interest on the national level in the development of “quantum technologies”:  devices that utilize quantum entanglement and superposition, often directed for the use of computation.  Advances in this field depend critically on the ability for such devices —qubits— to maintain coherence across long time scales.  Is there a natural limit to such coherence times?  Why are currently designed devices falling well short of theoretical expectations?  In this talk, I will explore the role that environmental radioactivity may be playing in limiting the coherence of superconducting qubits.  

I will share recent results from a dedicated set of measurements that show the interplay between natural radioactivity and coherence.  I will also discuss what measures can be taken to counteract these effects to enhance the performance of these essential devices.

slides - video recording


"Quantum Imaging"
una breve introduzione

Marco Genovese (INRiM, Torino, Italia)

May 24, 2021 - 17:00 CEST

Marco Genovese

Abstract and material

In questo seminario racconteremo la nascita e' lo sviluppo di una nuova tecnologia quantistica: il "quantum imaging", che si propone di migliorare le prestazioni dell'imaging tradizionale sfruttando le proprieta' peculiari degli stati ottici quantistici.  In particolare presenteremo alcuni schemi realizzati con fasci gemelli.

slides - video recording

Enrico Prati

Programming artificial intelligence on quantum computers

Enrico Prati
(Istituto di Fotonica e Nanotecnologie, CNR, Milano, Italia)

June 14, 2021 - 17:00 CEST

Quantum tecnologies


I review the the four architectures of quantum computers with their existing implementations, and the three deep learning paradigms respectively. Next, I introduce the concept of quantum artificial intelligence and I show some recent results, including a quantum perceptron and quantum restricted Bolzmann machines. I conclude by summarizing the directions and the perspectives to exploit quantum artificial intelligence in fields ranging from aerospace, to material design, to finance and many others.

Quantum computing at IBM: from single qubit manipulation to real application

Michele Grossi (IBM, Italia)

June 21, 2021 - 17:00 CEST

Michele Grossi
Fabrizio Illuminati

Webex conference link

Event number: 2671 750 1679 

Event password: Illumino 

Fabrizio Illuminati  (Università di Salerno) 

October 4, 2021 - 16:00 CEST

Dipartimento di Scienze dei Materiali, U5
Università di Milano-Bioocca
Seminar Room 1st floor

Abstract and material

Quantum entanglement comes in a variety of different forms and measures with different conceptual and operational interpretations. In this talk I will review some of the most relevant definitions of entanglement, the different physical effects that they characterize, and their use in the study of quantum many-body systems and models of quantum statistical mechanics.

slides - video recording

Dipartimento di Scienze dei Materiali, U5
Università di Milano-Bioocca
Seminar Room 1st floor

Using atom-like spins in semiconductors toward scalable quantum computing

Frederico Martins (Quantum Information Team Hitachi Cambridge Laboratory, UK)

November 30, 2021 - 13:30 CEST

Abstract and material

In a world where the amount of data to process is steadily increasing, the quantum nature of matter offers new possibilities to develop concepts, which may overcome nowadays technologies. Implications are expected in research areas that can range from quantum computation, cryptography, and quantum simulation.

To be useful, a qubit (the elementary quantum unit of information) needs to be both isolated from its environment and precisely controllable, which places strict requirements on its physical realization. In particular, spins in solids are one of the most promising realizations due to their potential for scalability and miniaturization. Furthermore, in these systems, quantum control has been established and electron spin coherence times now exceed several seconds. Even so, a critical challenge in these systems consists of developing a robust two-qubit gate that can be scaled up to a larger network.

In this seminar, I will overview some of the challenges of this field and introduce a new mechanism for “long-range” interaction. Making use of independent readout of two electron spins, we demonstrate coherent exchange interaction mediated by a multielectron quantum dot. This result provides a possible route to the realization of multi-qubit quantum circuits based on single spins.

slides - video recording