Exploring Quantum Optics with Superconducting Circuits

Abstract: 
Using modern micro and nano-fabrication techniques combined with superconducting materials we realize quantum electronic circuits in which we create, store, and manipulate individual microwave photons. Making use of the strong interaction engineered between photons and superconducting quantum two-level systems we probe fundamental quantum effects of microwave radiation and develop components for applications in quantum technology. In this presentation I will discuss methods for creating and characterizing individual propagating microwave frequency photons [1,2,3]. Using parametric amplifiers operating near the quantum limit [4] we fully reconstruct the quantum states of  propagating microwave fields and their entanglement [5] by exploring the statistics of the measured electromagnetic field amplitudes [6]. The methods which I present are not only applicable in the context of superconducting circuits but may be used to characterize any source of microwave frequency radiation, such as that emitted by inelastically tunneling electrons in semiconducting nano-structures, for example.

[1] D. Bozyigit et al., Nat. Phys. 7, 154 (2011)
[2] C. Lang et al., Phys. Rev. Lett. 106, 243601 (2011)
[3] M. Pechal et al., Phys. Rev. X 4, 041010 (2014)
[4] C. Eichler et al., Phys. Rev. Lett. 113, 110502 (2014)
[5] C. Lang et al., Nat. Phys. 9, 345–348 (2013) 
[6] C. Eichler et al., Phys. Rev. A 86, 032106 (2012)