Course data Course name: Quantum Computing Architectures Neptun ID: BMETE15MF60 Responsible teacher: András Pályi Department: Department of Theoretical Physics Programme: Courses for Physicist MSc students Course data sheet: BMETE15MF60 Requirements, Informations Course information - 2022 Fall Semester Lecturers: András Pályi, Péter Makk, Gergő Fülöp Responsible lecturer: András Pályi Language: English Location: F3M01 (seminar room of the Department of Theoretical Physics) Time: Wed 12:15-13:45 Requirements: quantum mechanics, solid state physics (semiconductors, bands, phonons). Detailed knowledge of superconductivity is not needed. Neptun Code: BMETE15MF60 Credits: 3 Exam: Short written test + oral exam. Contents Quantum bits Qubits, dynamics, measurement, polarization vector, composite systems, logical gates, circuits, algorithms. Control of quantum systems. Hamiltonians, propagators, and quantum gates. Larmor precession, Rabi oscillations, dispersive resonator shift in the Jaynes-Cummings model, exchange interaction, virtual photon exchange. Qubits based on the electron spin. Quantum dots, energy scales. Interactions: Zeeman, spin-orbit, hyperfine, electron-phonon, electron-electron. Coherent control of electron spins. Single-qubit gates: magnetic resonance, electrically driven spin resonance. Two-qubit gates: sqrt-of-swap via exchange interaction, CPhase. Error mechanisms during qubit control. Information loss mechanisms for electron spins. Qubit relaxation due to spin-orbit interaction and phonons. Qubit dephasing due to nuclear spins. Decoherence due to charge noise. Hahn echo and Car-Purcell-Meibloom-Gill (CPMG) schemes for prolonging the decoherence time. Novel spin qubit architectures Cavity/resonant readout, advanced material platforms. Introduction to superconductivity. Basics of superconductivity. Josephson junctions. Current-phase and voltage-phase Josephson relations. DC SQUID, energy terms. Charge qubit and transmon. Quantization of RF circuits, phase and charge as conjugate variables. Different regimes: flux, charge, phase. Control and readout of charge qubit and transmon. Single-qubit gates and dispersive readout via the resonator, Phonon-qubit coupling. Control and readout of transmon. Pulsed and continous readout, Stark shift, T1 and T2 measurements. Two-qubit gates, transmon-transmon coupling. Computing using transmon. State tomography, Bell inequalities, Entanglement, fidelity. Teleportation. Circuit quantum electrodynamics. Grover algorithm, error correction: repetition code, surface code. Quantum simulations Quantum computing architectures beyond Overview of the challenges, scaling. Other platforms: ion traps, NVs, photons. OUTDATED - Course information - 2020 Fall Semester Lecturers: András Pályi, Péter Makk, Gergő Fülöp Responsible lecturer: András Pályi Language: English Location: online, in Microsoft Teams Time: Wed 12:15-13:45 asynchronous. Requirements: quantum mechanics, solid state physics (semiconductors, bands, phonons). Detailed knowledge of superconductivity is not needed. Time: asynchronous. Neptun Code: BMETE15MF60 Credits: 3 Exam: Short written test + oral exam. Rules Each lecture (that is, each week) will have its own channel in Teams. Videos of the lectures will be uploaded to Teams, to the lecture's channel, by the official starting time of the lecture. For example, videos of lecture 1 will be uploaded by Sep 9 Wed 12:15. The total duration of the videos of a single lecture will be shorter than 90 minutes. From the above it follows that those of you who would be able follow the course synchronously will be able to do so: you can watch the video in the scheduled lecture time Wed 12:15-13:45. It is mandatory to watch the videos by the deadline Monday 23:00 following the lecture. (That is, you have a timespan of 5.5 days for that.) For example, it is mandatory to watch the videos of the first lecture by Sep 14 Mon 23:00. It is mandatory to complete a 10-question Kahoot quiz after watching each lecture, by the deadline Monday 23:00 following the lecture. The link to the weekly Kahoot quiz will be posted in the Teams channel of the lecture. Please use your real name or your neptun ID as your nickname in the Kahoot quiz. (It's okay not to do so if you have objections.) Please complete the test only once. The aim of the Kahoot quiz is (1) to give us feedback: did the students really watch the video? have the students understood the new concepts from the lecture? which quiz questions should be discussed on the subsequent lecture? (2) to give you feedback: have you understood the new concepts from the lecture? We strongly recommend that if you have the opportunity to follow the lecture synchronously, then do so: watch the video in the lecture time Wed 12:15-13:45, and complete the Kahoot quiz right away. Please do use the Teams channel of the lecture to ask questions, make remarks related to the lecture. We'll try to answer there. Using the channel (instead of, e.g., email) has the benefit that all participants can follow the discussion. Contents Quantum bits Qubits, dynamics, measurement, polarization vector, composite systems, logical gates, circuits, algorithms. Control of quantum systems. Hamiltonians, propagators, and quantum gates. Larmor precession, Rabi oscillations, dispersive resonator shift in the Jaynes-Cummings model, exchange interaction, virtual photon exchange. Qubits based on the electron spin. Quantum dots, energy scales. Interactions: Zeeman, spin-orbit, hyperfine, electron-phonon, electron-electron. Coherent control of electron spins. Single-qubit gates: magnetic resonance, electrically driven spin resonance. Two-qubit gates: sqrt-of-swap via exchange interaction, CPhase. Error mechanisms during qubit control. Information loss mechanisms for electron spins. Qubit relaxation due to spin-orbit interaction and phonons. Qubit dephasing due to nuclear spins. Decoherence due to charge noise. Hahn echo and Car-Purcell-Meibloom-Gill (CPMG) schemes for prolonging the decoherence time. Novel spin qubit architectures Cavity/resonant readout, advanced material platforms. Introduction to superconductivity. Basics of superconductivity. Josephson junctions. Current-phase and voltage-phase Josephson relations. DC SQUID, energy terms. Charge qubit and transmon. Quantization of RF circuits, phase and charge as conjugate variables. Different regimes: flux, charge, phase. Control and readout of charge qubit and transmon. Single-qubit gates and dispersive readout via the resonator, Phonon-qubit coupling. Control and readout of transmon. Pulsed and continous readout, Stark shift, T1 and T2 measurements. Two-qubit gates, transmon-transmon coupling. Computing using transmon. State tomography, Bell inequalities, Entanglement, fidelity. Teleportation. Circuit quantum electrodynamics. Grover algorithm, error correction: repetition code, surface code. Quantum simulations Quantum computing architectures beyond Overview of the challenges, scaling. Other platforms: ion traps, NVs, photons. OUTDATED - Course information - 2018 Fall Semester Lecturers: András Pályi, Péter Makk Responsible lecturer: András Pályi Language: English Location: building H, room H601 Time: Wednesdays, 12:15-13:45 Schedule: first lecture: Sep 5; no lecture on Sep 12, Sep 26, Oct 10, and nov 14; last lecture: Dec 5. Neptun Code: BMETE15MF60 Credits: 3 Exam: Short written test + oral exam. Dates: Dec 17, Jan 7, Jan 14, Jan 21. Exams start at 8:00am. Slides Quantum bits Control of quantum systems Qubits based on the electron spin Coherent control of electron spins Information loss mechanisms for electron spins Superconducting qubits: basic architectures Flux and charge qubits, cQED Qubit-qubit coupling State tomography Grover algorithm, quantum teleportation Literature T. Ihn: Semiconducting nanosctructures, Oxford University Press, 2010. Y.V. Nazarov, Y.M. Blanter: Quantum Transport: Introduction to Nanoscience, Cambridge University Press, 2009. Zwanenburg et al., Rev. Mod. Phys. 85, 961 (2013) Nanofizika tudásbázis