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TT: Fachverband Tiefe Temperaturen

TT 44: Transport: Quantum Coherence and Quantum Information

TT 44.18: Vortrag

Donnerstag, 26. März 2009, 19:00–19:15, HSZ 304

Cross-correlation heterodyne detection: Measuring microwave nontrivial propagating signals — Edwin P. Menzel¹, Matteo Mariantoni¹, Miguel Angel Araque Caballero¹, Frank Deppe¹, Elisabeth Hoffmann¹, Thomas Niemczyk¹, •Achim Marx¹, Rudolf Gross¹, and Enrique Solano² — ¹Walther-Meissner-Institut and TU Muenchen, Garching, Germany — ²Departamento de Quimica Fisica, Universidad del Pais Vasco / Euskal Herriko Unibertsitatea, Bilbao, Spain

The accurate measurement of the first two moments of Gaussian states (e.g., coherent or squeezed states) allows for their complete characterization. This provides a tool to clarify the quantum nature of microwave radiation, an important issue for example in circuit quantum electrodynamics. We present a full experimental characterization of nontrivial microwave signals with an average photon number of the order of 1, whose variance exhibits an elaborate dependence on external control parameters. We experimentally access the entire covariance matrix by splitting the input signals via microwave beam splitters and performing cross-correlation measurements. In this manner, we are able to precisely resolve the first two moments, a challenging task at microwave frequencies. Furthermore, we succeeded to measure the third central moment of similar nontrivial signals. We acknowledge support from SFB631, NIM, EuroSQUIP, and the Ikerbasque Foundation.