P. Carelli | University of L'Aquila (original) (raw)
Papers by P. Carelli
International Journal of Modern Physics B, 2000
We studied the escape process from the zero-voltage state to the running state in hysteretic dc-S... more We studied the escape process from the zero-voltage state to the running state in hysteretic dc-SQUIDs made with trilayer Nb-AlOx-Nb junctions. We analyze the experimental results, according to the thermal activation model, for devices having similar parameters except for the dimensionless inductance β L, which however is always very small. The interest in hysteretic dc-SQUIDs is in the possibility of using them to perform non-invasive measurements of the flux states in rf-SQUIDs: this achievement would be very important ...
Philosophical Magazine Part B, 2000
Abstract A new generation of astronomical detectors has recently been developed, on the basis of ... more Abstract A new generation of astronomical detectors has recently been developed, on the basis of superconducting tunnel junctions (STJs). STJs are capable of detecting photons in a wide range of wavelengths, from X-rays to infrared; also the counting of single photons in the optical range has been demonstrated. Since these detectors operate at very low temperature (down to 100 mK), a natural candidate for the read-out electronics is the dc superconducting quantum interference device (SQUID), an extremely sensitive ...
The Tenth Marcel Grossmann Meeting, On Recent Developments in Theoretical and Experimental General Relativity, Gravitation and Relativistic Field Theories - Proceedings of the MG10 Meeting, 2005
Abstract We report on the present status of the resonant gravitational waves detectors EXPLORER a... more Abstract We report on the present status of the resonant gravitational waves detectors EXPLORER and NAUTILUS operated by the ROG collaboration at CERN and at the INFN Frascati National Laboratories respectively. EXPLORER has been operating in continuous data taking for three years. NAUTILUS during 2002 underwent a partial overhaul of its read-out electronics. The results obtained since May 2003 show a considerable improvement in the performances of the apparatus. Both the detectors exhibit an unprecedented useful ...
Giornale italiano di cardiologia, 1980
Physical Review B, 1995
... Tech-nological details of the sample fabrication are described elsewhere. The samples were su... more ... Tech-nological details of the sample fabrication are described elsewhere. The samples were surrounded by a cryoperm shield with a residual field inside itof about 15 mOe. ... In general, increasing the temperature leads to a decrease 0 -60 -40 -20 0 20 H (moe) I 40 60 FIG. ...
Superconductor Science and Technology, 2001
Abstract Charge states in mesoscopic Josephson devices are considered promising candidates for a ... more Abstract Charge states in mesoscopic Josephson devices are considered promising candidates for a solid-state implementation of quantum computing. We studied three superconducting single electron transistors (SSETs) fabricated with small Al/AlOx/Al tunnel junctions, which, with a different choice of the construction parameters, can realize both the quantum bit and the readout system for the qubit charge state. We varied the junction capacitance and barrier transparency, making the Josephson energy EJ of the device ...
Il Nuovo Cimento D, 1997
We report on the design, fabrication and performance of a thin-film multiloop d.c.-SQUID, built i... more We report on the design, fabrication and performance of a thin-film multiloop d.c.-SQUID, built in such a way to realize an efficient shielding against uniform ambient fields. The multiloop geometry is a design which allows one to reduce the SQUID inductance. This is an important item to improve the device sensitivity towards the quantum limit, but it has the drawback of a lower coupling coefficient with the input coil, compared to other geometries such as the washer one. In this new design, we improve the design of the input coil to overcome the problem of the coupling and arrange the SQUID loops in a gradiometric configuration to obtain self-shielding of the device.
The resonant-mass gravitational wave detector NAUTILUS, operated by the ROG collaboration at the ... more The resonant-mass gravitational wave detector NAUTILUS, operated by the ROG collaboration at the INFN Frascati National Laboratories, is in continuous data taking since June 1998 with peak sensitivity of h ~= 3×10-22Hz-1/2. It has recently proven to be capable of recording signals due to the passage of cosmic rays. The results of the latest coincidence analyses between the NAUTILUS data
Quantum Computing and Quantum Bits in Mesoscopic Systems, 2004
Abstract: An rf-SQUID under appropriate temperature and bias conditions can be used to perform te... more Abstract: An rf-SQUID under appropriate temperature and bias conditions can be used to perform tests on macroscopic quantum coherence, or as a qubit element for quantum computing. For both these purposes it is necessary a readout system allowing to discriminate stroboscopically the rf-SQUID state with high fidelity. This task can be performed by means of a hysteretic dc-SQUID inductively coupled to the rf-SQUID and turned on by a fast bias current pulse. We have proposed and realized an integrated ...
International Journal of Modern Physics B, 1999
The new generation of astronomical detectors based on Superconducting Tunnel Junctions (STJs) is ... more The new generation of astronomical detectors based on Superconducting Tunnel Junctions (STJs) is capable of detecting photons in a wide range of wavelengths, and, in some cases, even of counting single photons. Since these detectors operate at very low temperature (down to 100 mK), a natural candidate for the readout electronics is the dc-SQUID, a superconducting device that can work as a current preamplifier, reaching very good noise performance. In this paper we present measurements on a homemade dc-SQUID, ...
International Journal of Modern Physics B, 2003
Computing tools, all based on classical logic at the moment, present intrinsic limitations that c... more Computing tools, all based on classical logic at the moment, present intrinsic limitations that can be overcome by using quantum logic. In this direction, superconducting Josephson devices have been proved to be very suitable candidates for the realization of quantum computing tools. We present some basic elements of quantum computing, possible strategies for the implementation of quantum gates by using Josephson devices, and recent experimental results in this field.
Physical Review B, 1987
A computer simulation of a dc superconducting quantum interference device (dc SQUID) in the case ... more A computer simulation of a dc superconducting quantum interference device (dc SQUID) in the case betac=3, betaL=6.28, and noise parameter Gamma=0.01 is performed. The main difference with respect to the case of noiseless behavior is the disappearing and/or mixing of some solutions of the differential equations describing the time evolution of the system. Only by including the noise effect in the simulation is it possible to understand the working mechanism of some practical devices characterized by high values of the critical current and inductance.
New Journal of Physics, 2009
We experimentally demonstrate the coherent oscillations of a tunable superconducting flux qubit b... more We experimentally demonstrate the coherent oscillations of a tunable superconducting flux qubit by manipulating its energy potential with a nanosecond-long pulse of magnetic flux. The occupation probabilities of two persistent current states oscillate at a frequency ranging from 6 GHz to 21 GHz, tunable via the amplitude of the flux pulse. The demonstrated operation mode allows to realize quantum gates which take less than 100 ps time and are thus much faster compared to other superconducting qubits. An other advantage of this type of qubit is its insensitivity to both thermal and magnetic field fluctuations.
Superconductor Science and Technology, 2003
Abstract In recent years, the quantum behaviour of Josephson devices has been the object of thoro... more Abstract In recent years, the quantum behaviour of Josephson devices has been the object of thorough experimental investigation, mainly with the objective of studying quantum mechanics in macroscopic objects. At present, the same quantum properties are being exploited with the aim of the physical implementation of quantum bits and quantum registers. Here we present measurements on a system containing potential qubits, namely a rf SQUID and a hysteretic dc SQUID, magnetically coupled, under microwave excitation; the devices ...
International Journal of Modern Physics B, 2000
We studied the escape process from the zero-voltage state to the running state in hysteretic dc-S... more We studied the escape process from the zero-voltage state to the running state in hysteretic dc-SQUIDs made with trilayer Nb-AlOx-Nb junctions. We analyze the experimental results, according to the thermal activation model, for devices having similar parameters except for the dimensionless inductance β L, which however is always very small. The interest in hysteretic dc-SQUIDs is in the possibility of using them to perform non-invasive measurements of the flux states in rf-SQUIDs: this achievement would be very important ...
Philosophical Magazine Part B, 2000
Abstract A new generation of astronomical detectors has recently been developed, on the basis of ... more Abstract A new generation of astronomical detectors has recently been developed, on the basis of superconducting tunnel junctions (STJs). STJs are capable of detecting photons in a wide range of wavelengths, from X-rays to infrared; also the counting of single photons in the optical range has been demonstrated. Since these detectors operate at very low temperature (down to 100 mK), a natural candidate for the read-out electronics is the dc superconducting quantum interference device (SQUID), an extremely sensitive ...
The Tenth Marcel Grossmann Meeting, On Recent Developments in Theoretical and Experimental General Relativity, Gravitation and Relativistic Field Theories - Proceedings of the MG10 Meeting, 2005
Abstract We report on the present status of the resonant gravitational waves detectors EXPLORER a... more Abstract We report on the present status of the resonant gravitational waves detectors EXPLORER and NAUTILUS operated by the ROG collaboration at CERN and at the INFN Frascati National Laboratories respectively. EXPLORER has been operating in continuous data taking for three years. NAUTILUS during 2002 underwent a partial overhaul of its read-out electronics. The results obtained since May 2003 show a considerable improvement in the performances of the apparatus. Both the detectors exhibit an unprecedented useful ...
Giornale italiano di cardiologia, 1980
Physical Review B, 1995
... Tech-nological details of the sample fabrication are described elsewhere. The samples were su... more ... Tech-nological details of the sample fabrication are described elsewhere. The samples were surrounded by a cryoperm shield with a residual field inside itof about 15 mOe. ... In general, increasing the temperature leads to a decrease 0 -60 -40 -20 0 20 H (moe) I 40 60 FIG. ...
Superconductor Science and Technology, 2001
Abstract Charge states in mesoscopic Josephson devices are considered promising candidates for a ... more Abstract Charge states in mesoscopic Josephson devices are considered promising candidates for a solid-state implementation of quantum computing. We studied three superconducting single electron transistors (SSETs) fabricated with small Al/AlOx/Al tunnel junctions, which, with a different choice of the construction parameters, can realize both the quantum bit and the readout system for the qubit charge state. We varied the junction capacitance and barrier transparency, making the Josephson energy EJ of the device ...
Il Nuovo Cimento D, 1997
We report on the design, fabrication and performance of a thin-film multiloop d.c.-SQUID, built i... more We report on the design, fabrication and performance of a thin-film multiloop d.c.-SQUID, built in such a way to realize an efficient shielding against uniform ambient fields. The multiloop geometry is a design which allows one to reduce the SQUID inductance. This is an important item to improve the device sensitivity towards the quantum limit, but it has the drawback of a lower coupling coefficient with the input coil, compared to other geometries such as the washer one. In this new design, we improve the design of the input coil to overcome the problem of the coupling and arrange the SQUID loops in a gradiometric configuration to obtain self-shielding of the device.
The resonant-mass gravitational wave detector NAUTILUS, operated by the ROG collaboration at the ... more The resonant-mass gravitational wave detector NAUTILUS, operated by the ROG collaboration at the INFN Frascati National Laboratories, is in continuous data taking since June 1998 with peak sensitivity of h ~= 3×10-22Hz-1/2. It has recently proven to be capable of recording signals due to the passage of cosmic rays. The results of the latest coincidence analyses between the NAUTILUS data
Quantum Computing and Quantum Bits in Mesoscopic Systems, 2004
Abstract: An rf-SQUID under appropriate temperature and bias conditions can be used to perform te... more Abstract: An rf-SQUID under appropriate temperature and bias conditions can be used to perform tests on macroscopic quantum coherence, or as a qubit element for quantum computing. For both these purposes it is necessary a readout system allowing to discriminate stroboscopically the rf-SQUID state with high fidelity. This task can be performed by means of a hysteretic dc-SQUID inductively coupled to the rf-SQUID and turned on by a fast bias current pulse. We have proposed and realized an integrated ...
International Journal of Modern Physics B, 1999
The new generation of astronomical detectors based on Superconducting Tunnel Junctions (STJs) is ... more The new generation of astronomical detectors based on Superconducting Tunnel Junctions (STJs) is capable of detecting photons in a wide range of wavelengths, and, in some cases, even of counting single photons. Since these detectors operate at very low temperature (down to 100 mK), a natural candidate for the readout electronics is the dc-SQUID, a superconducting device that can work as a current preamplifier, reaching very good noise performance. In this paper we present measurements on a homemade dc-SQUID, ...
International Journal of Modern Physics B, 2003
Computing tools, all based on classical logic at the moment, present intrinsic limitations that c... more Computing tools, all based on classical logic at the moment, present intrinsic limitations that can be overcome by using quantum logic. In this direction, superconducting Josephson devices have been proved to be very suitable candidates for the realization of quantum computing tools. We present some basic elements of quantum computing, possible strategies for the implementation of quantum gates by using Josephson devices, and recent experimental results in this field.
Physical Review B, 1987
A computer simulation of a dc superconducting quantum interference device (dc SQUID) in the case ... more A computer simulation of a dc superconducting quantum interference device (dc SQUID) in the case betac=3, betaL=6.28, and noise parameter Gamma=0.01 is performed. The main difference with respect to the case of noiseless behavior is the disappearing and/or mixing of some solutions of the differential equations describing the time evolution of the system. Only by including the noise effect in the simulation is it possible to understand the working mechanism of some practical devices characterized by high values of the critical current and inductance.
New Journal of Physics, 2009
We experimentally demonstrate the coherent oscillations of a tunable superconducting flux qubit b... more We experimentally demonstrate the coherent oscillations of a tunable superconducting flux qubit by manipulating its energy potential with a nanosecond-long pulse of magnetic flux. The occupation probabilities of two persistent current states oscillate at a frequency ranging from 6 GHz to 21 GHz, tunable via the amplitude of the flux pulse. The demonstrated operation mode allows to realize quantum gates which take less than 100 ps time and are thus much faster compared to other superconducting qubits. An other advantage of this type of qubit is its insensitivity to both thermal and magnetic field fluctuations.
Superconductor Science and Technology, 2003
Abstract In recent years, the quantum behaviour of Josephson devices has been the object of thoro... more Abstract In recent years, the quantum behaviour of Josephson devices has been the object of thorough experimental investigation, mainly with the objective of studying quantum mechanics in macroscopic objects. At present, the same quantum properties are being exploited with the aim of the physical implementation of quantum bits and quantum registers. Here we present measurements on a system containing potential qubits, namely a rf SQUID and a hysteretic dc SQUID, magnetically coupled, under microwave excitation; the devices ...