Berlin 2018 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 17: Superconductivity: Qubits II
TT 17.8: Talk
Monday, March 12, 2018, 16:45–17:00, H 2053
Quantum Process Tomography of a Quantum Memory — •Michael Renger1,2, Edwar Xie1,2,3, Frank Deppe1,2,3, Peter Eder1,2,3, Michael Fischer1,2,3, Stefan Pogorzalek1,2, Kirill G. Fedorov1,2, Achim Marx1, and Rudolf Gross1,2,3 — 1Walther-Meißner-Institut, Bayerische Akademie der Wissenschaften, 85748 Garching, Germany — 2Physik-Department, TU München, 85748 Garching, Germany — 3Nanosystems Initiative Munich (NIM), 80799 München, Germany
In order to realize a quantum memory, a memory protocol for a superconducting qubit coupled to a 3D cavity resonator is realized with a Z fidelity of 85%. By exploiting the multimode structure of the 3D cavity, we combine readout and storage capability in a single device, thereby significantly enhancing scalability. With the goal of accurately characterizing the information loss during the protocol, the overall process fidelity has to be measured. To this end, we perform quantum process tomography on our quantum memory system. The protocol consists of four pulses with a total length of 240ns. The qubit density matrix is reconstructed with standard quantum state tomography for a suitable set of qubit states. The comparison of the measured outcome with the theoretical value gives us knowledge about the process matrix χ. We present tomography data and compare the quantum process fidelity to the Z fidelity.
The authors acknowledge support from DFG through FE 1564/1-1, the doctorate program ExQM of the Elite Network of Bavaria and the IMPRS ‘Quantum Science and Technology’.