Transferring the state of an information carrier between two parties is an essential primitive in both classical and quantum communication and information processing. Quantum teleportation describes the concept of transferring an unknown quantum state from a sender to a physically separated receiver without transmitting the physical carrier of information itself.

Suppose you leave your house in Zurich early in the morning, and you set off walking in a random direction, without a compass, GPS or looking at the signs. What is the probability of ending up in your lab at ETH Zurich’s Hoenggerberg Campus? And what is your probability of ending up for example at the ETH main building? Either one is not very high, certainly. Now suppose you wake up in a tunnel directly connecting the two sites. How does this affect your chances to end up at either place?

Independent of the physical system, experiments that explore quantum mechanical effects at the single quantum limit need to fulfil a set of different criteria. Various systems such as neutral or charged atoms, superconducting circuits, nuclear spins, NV-centers or quantum dots, offer a diversity of physical properties to meet these requirements. For example, an important prerequisite for any quantum mechanical experiment is the fast and coherent manipulation of a set of quanta at time scales shorter than the coherence time of the system.

In recent years, hybrid circuit QED devices consisting of semiconductor double quantum dots coupled to microwave cavities have attracted a lot of attention. However, an important milestone that has not been reach with these systems is the strong coupling regime of cavity QED. Reaching this regime is challenging with quantum dots due to the lack of control over the decoherence mechanisms limiting charge relaxation and dephasing rates.

A coherent link between spatially separated nodes of a quantum network may be realized using itinerant photons as information carriers [1]. The necessary efficient absorption at the receiving node can be achieved by using a photon with a suitable temporal profile allowing time-reversal of the emission process [2].

Quantum simulations are expected to vastly outperform classical simulations when modeling the dynamics of interacting spin systems. Researchers have used a digital quantum simulation to show that spin dynamics can be studied and predicted, which lays the groundwork for applications in quantum magnetism and strongly correlated systems.

Talking to friends in a crowded venue is sometimes difficult: the information one tries to get across gets washed out in the noisy environment. In this respect, quantum systems are no different. When they interact with the environment, they are subject to dephasing which ultimately destroys the information they hold. 

Entanglement correlations between particles constitute one of the most striking phenomena in quantum physics. Many key properties of materials, such as superconductivity or magnetism, are governed by those intricate quantum relations between particles. Understanding and modeling these complex properties are often based on a systematic restriction of the underlying parameter space to its relevant part. Here, we explore this concept using a quantum computing device rather than a classical computer.

In this article, we present a simple technique that measures static and microwave field distributions on a mm-scale and with a resolution of approximately 100 micrometer in the vicinity of a superconducting, chip-based microwave guide.