Categoria

Lezioni di dottorato

Data

1 Luglio 2020 15:00 - 17:00

Luogo

Microsoft Teams

Affiliation

Universita` di Salerno, Dipartimento di Fisica

Area di Ricerca

2020-7-1 15:00:00

Part 1: Josephson effect and non-linear dynamics. (Guarcello)

The Josephson effect describes the tunneling of Cooper pairs between two superconductors separated by a non-superconducting layer. A good description of the associated circuit element is given by an equation with a non-linear sinusoidal term, analogous to the equation of the physical pendulum. In the course we will start from this formulation to describe the electrical properties of the single Josephson element, of the Josephson transmission lines and of the exquisitely non-linear phenomena that occur: soliton, chaos, and the coherent synchronization of oscillations. Finally, working principles and potential applications of a SQUID, namely, a device formed by inserting one or more Josephson junctions in a superconducting ring, will be described in detail in the lectures.

Part 2: Superconducting electronics (Pagano)

Superconductivity is a state of matter of an exquisitely quantum nature. Since its discovery, many applications of great practical interest have been developed. In addition to recalling "power" applications, involving high currents and magnetic fields, attention will be focused on the most exquisitely "electronic" applications, which are largely based on the exploitation of quantum properties on a macroscopic scale. Examples of applications of superconductors such as magnetic sensors, radiation detectors and digital circuits (classical and quantum) will be analyzed in detail. The main applications in the fields of telecommunications, astronomy, medicine and materials science will also be illustrated.

Part 3: superconducting qubits (Citro)

Superconducting qubits are solid state electrical circuits fabricated using techniques borrowed from conventional integrated circuits. They are based on the Josephson tunnel junction, the only non-dissipative, strongly non-linear circuit element available at low temperature. In contrast to microscopic entities such as spins or atoms, they tend to be well coupled to other circuits, which make them appealing from the point of view of readout and gate implementation. Very recently, new designs of superconducting qubits based on multi-junction circuits have solved the problem of isolation from unwanted extrinsic electromagnetic perturbations. We discuss in this lectures the basic quantum circuits theory, the superconducting qubit model and finally tacke the effect of decoherence.

The Josephson effect describes the tunneling of Cooper pairs between two superconductors separated by a non-superconducting layer. A good description of the associated circuit element is given by an equation with a non-linear sinusoidal term, analogous to the equation of the physical pendulum. In the course we will start from this formulation to describe the electrical properties of the single Josephson element, of the Josephson transmission lines and of the exquisitely non-linear phenomena that occur: soliton, chaos, and the coherent synchronization of oscillations. Finally, working principles and potential applications of a SQUID, namely, a device formed by inserting one or more Josephson junctions in a superconducting ring, will be described in detail in the lectures.

Part 2: Superconducting electronics (Pagano)

Superconductivity is a state of matter of an exquisitely quantum nature. Since its discovery, many applications of great practical interest have been developed. In addition to recalling "power" applications, involving high currents and magnetic fields, attention will be focused on the most exquisitely "electronic" applications, which are largely based on the exploitation of quantum properties on a macroscopic scale. Examples of applications of superconductors such as magnetic sensors, radiation detectors and digital circuits (classical and quantum) will be analyzed in detail. The main applications in the fields of telecommunications, astronomy, medicine and materials science will also be illustrated.

Part 3: superconducting qubits (Citro)

Superconducting qubits are solid state electrical circuits fabricated using techniques borrowed from conventional integrated circuits. They are based on the Josephson tunnel junction, the only non-dissipative, strongly non-linear circuit element available at low temperature. In contrast to microscopic entities such as spins or atoms, they tend to be well coupled to other circuits, which make them appealing from the point of view of readout and gate implementation. Very recently, new designs of superconducting qubits based on multi-junction circuits have solved the problem of isolation from unwanted extrinsic electromagnetic perturbations. We discuss in this lectures the basic quantum circuits theory, the superconducting qubit model and finally tacke the effect of decoherence.

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