BEGIN:VCALENDAR VERSION:2.0 PRODID:-//CERN//INDICO//EN BEGIN:VEVENT SUMMARY:Fast high fidelity quantum non-demolition qubit readout via a non- perturbative cross-Kerr coupling DTSTART;VALUE=DATE-TIME:20190620T140000Z DTEND;VALUE=DATE-TIME:20190620T143000Z DTSTAMP;VALUE=DATE-TIME:20260608T022404Z UID:indico-contribution-35-247@cern.ch DESCRIPTION:Speakers: Rémy Dassonneville (Institut Néel)\nQubit readout is an indispensable element of any quantum information processor. In this work\,\nwe propose an original coupling scheme between a qubit and a cavi ty mode based on a non-perturbative\ncross-Kerr interaction. This scheme\, using the same experimental techniques as the perturbative cross-Kerr cou pling (dispersive interaction)\, leads to an alternative readout mechanism for superconducting qubits. This\nnew process\, being non-perturbativ e\, maximizes the speed of qubit readout\, its single-shot readout fid elity and\nits quantum non-demolition (QND) behavior at the same time\, wh ile minimizing the effect of unwanted decay channels such as\, for example \, the Purcell effect. We observed 97.4 % single-shot\nreadout fidel ity for short 50 ns pulses. Using long measurement\, we quantifi ed the QND-ness to\n99 %.\n\nhttps://indico.unina.it/event/18/contribut ions/247/ LOCATION:Strand Hotel Terme Delfini URL:https://indico.unina.it/event/18/contributions/247/ END:VEVENT BEGIN:VEVENT SUMMARY:Superconducting Quantum-Classical Information Processing Systems DTSTART;VALUE=DATE-TIME:20190620T143000Z DTEND;VALUE=DATE-TIME:20190620T150000Z DTSTAMP;VALUE=DATE-TIME:20260608T022404Z UID:indico-contribution-35-220@cern.ch DESCRIPTION:Speakers: Oleg Mukhanov (SeeQC)\nTraditionally\, the control a nd measurement of superconducting quantum devices including arrays of qubi ts are done using room-temperature classical electronics connected to cryo genic environment via high fidelity cables. This poses daunting technical challenges to quantum system scaling as the heat load\, latency\, noise as sociated with bringing signals in and out of the cryostat rise dramaticall y with number of quantum devices. By integrating the control and readout e lectronics into the cryostat in proximity to quantum devices\, these probl ems can be drastically reduced to enable large-scale quantum arrays. This can finally lead to quantum processing systems that can outperform the bes t available classical supercomputers. Superconducting Single Flux Quantum (SFQ) digital logic can be a basis for the implementation of a proximal c lassical co-processor for low-overhead qubit control and measurement. SFQ digital circuits also can perform in situ classical processing of the resu lts of quantum measurement to enable fast error tracking and feedback to s tabilize the quantum array. Furthermore\, hybrid quantum-classical systems integrating together the quantum and classical processing hardware units can match to various application algorithm architectures which typically c ombine quantum and classical algorithmic modules. Latest results in the S FQ-based digital control of superconducting qubits will be presented. The implementation of a scalable quantum-classical 3D integrated system extend ing across multiple temperature stages will be discussed.\n\nhttps://indic o.unina.it/event/18/contributions/220/ LOCATION:Strand Hotel Terme Delfini URL:https://indico.unina.it/event/18/contributions/220/ END:VEVENT BEGIN:VEVENT SUMMARY:Identifying and Controlling Sources of Decoherence In Superconduct ing Quantum Devices. DTSTART;VALUE=DATE-TIME:20190620T133000Z DTEND;VALUE=DATE-TIME:20190620T140000Z DTSTAMP;VALUE=DATE-TIME:20260608T022404Z UID:indico-contribution-35-204@cern.ch DESCRIPTION:Speakers: Sergey Kubatkin (Chalmers University of Technology)\ nDespite the promises of superconducting qubits\, their performance is pre sently limited by short coherence times due to defects intrinsic to materi als. As a result\, future quantum computers would require massive error co rrection circuits\, which seem to be very challenging to build. Another mo re promising path would be to improve this coherence time\, which would re lax the constraints on the quantum error correction circuits and would thu s make a quantum computer more feasible. This task is considered one of th e main challenges in the field. Our recent results [1] gave vital clues to the long-standing problem of noise and decoherence in superconducting dev ices: a technique for on-chip Electron Spin Resonance (ESR) [2]\, allowed to identify\, for the first time\, the chemical species responsible for th e flux noise in superconducting circuits [3]. Furthermore\, the most recen t noise measurements in superconducting resonators point to the link betwe en charge and flux noise in superconducting circuits [3]: a mild sample tr eatment has lead to tenfold reduction of the surface spins\, responsible f or the flux noise\, as evidenced by ESR\, and this treatment has also lead to tenfold reduction of the low frequency noise in superconducting resona tor\, usually associated with the charge noise. The chemical identificatio n of the possible remaining sources of noise in superconducting devices al lows for an active chemical intervention\, aiming at silencing the defects and\, therefore\, improving the coherence in superconducting quantum devi ces.\n\n[1] Phys. Rev. Lett. 118\, 057703\, (2017)\n[2] Journ. of Appl. Ph ys. 112\, 123905\, (2012)\n[3] Phys. Rev. Lett. 118\, 057702\, (2017)\n[4] Nature Comms. 9\, 1143\, (2018)\n\nhttps://indico.unina.it/event/18/contr ibutions/204/ LOCATION:Strand Hotel Terme Delfini URL:https://indico.unina.it/event/18/contributions/204/ END:VEVENT END:VCALENDAR