Impact of time-ordered measurements of the two states in a niobium superconducting qubit structure

Abstract

Measurements of thermal activation are made in a superconducting, niobium Persistent-Current (PC) qubit structure, which has two stable classical states of equal and opposite circulating current. The magnetization signal is read out by ramping the bias current of a DC SQUID. This ramping causes time-ordered measurements of the two states, where measurement of one state occurs before the other. This time-ordering results in an effective measurement time, which can be used to probe the thermal activation rate between the two states. Fitting the magnetization signal as a function of temperature and ramp time allows one to estimate a quality factor of 10^6 for our devices, a value favorable for the observation of long quantum coherence times at lower temperatures.

arXiv comment14 pages, 4 figures

References in corpus (2)

• Manipulating the Quantum State of an Electrical Circuit
• A Superconducting Persistent Current Qubit

Cited by in corpus (6)

• Probing Decoherence with Electromagnetically Induced Transparency in Superconductive Quantum Circuits
• Electromagnetically induced transparency in superconducting quantum circuits : Effects of decoherence, tunneling and multi-level cross-talk
• Energy Relaxation Time between Macroscopic Quantum Levels in a Superconducting Persistent Current Qubit
• Stationary entanglement in strongly coupled qubits
• DC measurements of macroscopic quantum levels in a superconducting qubit structure with a time-ordered meter
• Material matters in superconducting qubits