Cavity Quantum Electrodynamics (CQED)-Based Quantum LDPC Encoders
CQED Susceptibility of Superconducting Transmons coupled to a Microstrip Resonator Cavity David...
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Transcript of CQED Susceptibility of Superconducting Transmons coupled to a Microstrip Resonator Cavity David...
![Page 1: CQED Susceptibility of Superconducting Transmons coupled to a Microstrip Resonator Cavity David Pappas, Martin Sandberg, Jiansong Gao, Michael Vissers.](https://reader035.fdocuments.us/reader035/viewer/2022062712/56649ca65503460f94967b1f/html5/thumbnails/1.jpg)
cQED Susceptibility of Superconducting Transmons coupled to a Microstrip Resonator Cavity
David Pappas, Martin Sandberg, Jiansong Gao, Michael VissersNIST, Boulder, CO 80303
Anton Kockum, Goran JohanssonChalmers University of Technology, Gӧteborg, Sweden
![Page 2: CQED Susceptibility of Superconducting Transmons coupled to a Microstrip Resonator Cavity David Pappas, Martin Sandberg, Jiansong Gao, Michael Vissers.](https://reader035.fdocuments.us/reader035/viewer/2022062712/56649ca65503460f94967b1f/html5/thumbnails/2.jpg)
OutlineWhat do you do when your qubit
frequency is too close to your cavity? “Quantum art”
• Response of a coupled qubit-cavity system to a strong drive at finite temperature– Singly dressed - qubit + cavity– Doubly dressed system –
• qubit+cavity+ drive• two photon processes
– Triply dressed• three photon processes
![Page 3: CQED Susceptibility of Superconducting Transmons coupled to a Microstrip Resonator Cavity David Pappas, Martin Sandberg, Jiansong Gao, Michael Vissers.](https://reader035.fdocuments.us/reader035/viewer/2022062712/56649ca65503460f94967b1f/html5/thumbnails/3.jpg)
“2½D” - Transmon coupled to microstrip cavity• Standard large-pad transmon,
GHz• Measured with microstrip cavity
– Measured at 20 mK– Radiation decay suppressed due to
proximity of ground plane• T1 2 - 10 s
– Coupling strength MHz– = 6.525 Ghz
• – Lifetime strongly Purcell limited– In resonant regime (not dispersive)
Sandberg, et al., APL 102, 072601 (2013)
Qubit
![Page 4: CQED Susceptibility of Superconducting Transmons coupled to a Microstrip Resonator Cavity David Pappas, Martin Sandberg, Jiansong Gao, Michael Vissers.](https://reader035.fdocuments.us/reader035/viewer/2022062712/56649ca65503460f94967b1f/html5/thumbnails/4.jpg)
Cavity response to a probe toneVNA S21
probe
1 2
• Measure transmission, S21 at T∽100 mK• Susceptibility of the system
• frequency & power dependence• High power – bare cavity• Low power – excitation spectrum of
“singly dressed” qubit+cavity
cavity
Qubit-cavity excitations
High power
Low power
![Page 5: CQED Susceptibility of Superconducting Transmons coupled to a Microstrip Resonator Cavity David Pappas, Martin Sandberg, Jiansong Gao, Michael Vissers.](https://reader035.fdocuments.us/reader035/viewer/2022062712/56649ca65503460f94967b1f/html5/thumbnails/5.jpg)
Model with Jaynes-Cummings Hamiltonian• Include 4 lowest qubit states, ,,, 3 lowest photon numbers in cavity, ,,
Excitation spectrum Transition Frequency (GHz)
0 - 7 18.5350 - 6 17.6500 - 5 13.2250 - 4 12.6601 - 7 12.4310 - 3 12.0032 - 7 11.9191 - 6 11.5462 - 6 11.0341 - 5 7.1210 - 2 6.6162 - 5 6.6091 - 4 6.5563 - 7 6.5320 - 1 6.1042 - 4 6.0441 - 3 5.8994 - 7 5.8753 - 6 5.6472 - 3 5.3875 - 7 5.3104 - 6 4.9905 - 6 4.4253 - 5 1.2226 - 7 0.8853 - 4 0.6574 - 5 0.5651 - 2 0.512
![Page 6: CQED Susceptibility of Superconducting Transmons coupled to a Microstrip Resonator Cavity David Pappas, Martin Sandberg, Jiansong Gao, Michael Vissers.](https://reader035.fdocuments.us/reader035/viewer/2022062712/56649ca65503460f94967b1f/html5/thumbnails/6.jpg)
Line identificationTransition Frequency (GHz)
0 - 7 18.5350 - 6 17.6500 - 5 13.2250 - 4 12.6601 - 7 12.4310 - 3 12.0032 - 7 11.9191 - 6 11.5462 - 6 11.0341 - 5 7.1210 - 2 6.6162 - 5 6.6091 - 4 6.5563 - 7 6.5320 - 1 6.1042 - 4 6.0441 - 3 5.8994 - 7 5.8753 - 6 5.6472 - 3 5.3875 - 7 5.3104 - 6 4.9905 - 6 4.4253 - 5 1.2226 - 7 0.8853 - 4 0.6574 - 5 0.5651 - 2 0.512
cavitycavity
0-21-43-7
• Use low power probe tone to measure the system
• Add high power drive (i.e. pump) for susceptibilty
![Page 7: CQED Susceptibility of Superconducting Transmons coupled to a Microstrip Resonator Cavity David Pappas, Martin Sandberg, Jiansong Gao, Michael Vissers.](https://reader035.fdocuments.us/reader035/viewer/2022062712/56649ca65503460f94967b1f/html5/thumbnails/7.jpg)
Susceptibility measurementVNA S21
probe
1 2
drive
Drive tone, D (GHz)