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Updated: Jun 5, 2026

Generation and Coherent Control of Pulsed Quantum Frequency Combs
Published on: June 8, 2018
Measuring the temperature dependence of individual two-level systems by direct coherent control
J Lisenfeld1, C Müller, J H Cole
1Physikalisches Institut, Karlsruhe Institute of Technology, D-76128 Karlsruhe, Germany.
Abstract:
We demonstrate a new method to directly manipulate the state of individual two-level systems (TLSs) in phase qubits. It allows one to characterize the coherence properties of TLSs using standard microwave pulse sequences, while the qubit is used only for state readout. We apply this method to measure the temperature dependence of TLS coherence for the first time. The energy relaxation time T1 is found to decrease quadratically with temperature for the two TLSs studied in this work, while their dephasing time measured in Ramsey and spin-echo experiments is found to be T1 limited at all temperatures.
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