Quantum theory of a bandpass Purcell filter for qubit readout

The readout fidelity of superconducting transmon and Xmon qubits is partially limited by the qubit energy relaxation through the resonator into the transmission line, which is also known as the Purcell effect. One way to suppress this energy relaxation is to employ a filter which impedes microwave propagation at the qubit frequency. We present semiclassical and quantum analyses for the bandpass Purcell filter realized by E.\ Jeffrey \textit{et al}.\ [Phys.\ Rev.\ Lett.\ 112, 190504 (2014)]. For typical experimental parameters, the bandpass filter suppresses the qubit relaxation rate by up to two orders of magnitude while maintaining the same measurement rate. We also show that in the presence of a microwave drive the qubit relaxation rate further decreases with increasing drive strength.Comment: 15 pages, 4 figures; published versio

Purcell effect with microwave drive: Suppression of qubit relaxation rate

We analyze the Purcell relaxation rate of a superconducting qubit coupled to a resonator, which is coupled to a transmission line and pumped by an external microwave drive. Considering the typical regime of the qubit measurement, we focus on the case when the qubit frequency is significantly detuned from the resonator frequency. Surprisingly, the Purcell rate decreases when the strength of the microwave drive is increased. This suppression becomes significant in the nonlinear regime. In the presence of the microwave drive, the loss of photons to the transmission line also causes excitation of the qubit; however, the excitation rate is typically much smaller than the relaxation rate. Our analysis also applies to a more general case of a two-level quantum system coupled to a cavity.Comment: Published versio

A Multivariate Probit Analysis of Selected Factors Influencing Electronic Commerce Adoption in Organizations

This study investigates factors leading to the go/no go decision on organizational innovations, with particular reference to Electronic Commerce (E-Commerce). The goal is to explore important antecedents promoting the adoption of technological innovations and to extend the frontiers of knowledge in this area, by integrating two major research paradigms - basic and applied. Randomly selected organizations in the IT area participated in the study. Variables pertaining to organizations. Information Technology, and users of the technology were assessed and analyzed using an omnibus instrument and probit analysis respectively. This study provides a tentative elucidation of contemporary unresolved issues, and also broadens understanding in the assimilation of emerging technologies into organizations