Thursday 16 July; Delft, Konrad Lehnert 'Amplification, squeezing and entanglement generation with electrical circuits'



Location: Zaal F

Time: 16:00 hrs

In an increasing number of experiments, information is encoded in the modulation of a pure quantum state of a microwave signal. For example, the state of superconducting qubits and the position of mechanical oscillators have been efficiently encoded into number states or coherent states of the microwave field. In contrast, the ability to extract the information from the microwave signal is not as advanced. The best available microwave measurement technology introduces noise twenty times larger than the quantum fluctuations present in the microwave field. In this talk, I will describe our effort to develop tools for measuring microwave signals that introduce much less noise than the microwave quantum fluctuations. The key element of these tools is a type of Josephson parametric amplifier (JPA), which we have recently created and studied. While Josephson parametric amplifiers had been studied for many years, they had never been employed to improve another measurement. I will show that our lab is now using these amplifiers to dramatically improve two measurements. First, we use the JPA to sense nanomechanical motion with greatly enhanced precision. Second, we use the JPA to tomographically reconstruct a squeezed state of a microwave field, which was itself created with a JPA. Because pairs of squeezed states can be combined to create entangled modes of the microwave field, they form the basis of a general quantum information processing strategy. Our lab is evaluating this strategy, known as continuous variables quantum information, by attempting to realize quantum teleportation between microwave electrical circuits.