Quantum correlations, i.e. entanglement, appears in many natural and experimental physical situations and is an ingredient in quantum computation. Their appearance marks the establishment of a qualitatively different behaviour - be it a new phase, such as a BEC, or a resource for impossible computations. I will give an overview of a range of contexts where entanglement plays such a role. Finally, I will discuss claims that quantum correlations lead to a violation of the second law of thermodynamics and with it Landauer's erasure principle. I will argue why these claims are erroneous and show how a consistent treatment of correlations in this thermodynamical context resolves the paradoxical situation.

A single point-like detector can be used to determine absolute acceleration by local measurements on a quantum field. To show this, we consider two kinematically indistinguishable scenarios: an inertial observer, Bob, measuring the field of an uniformly accelerated cavity, and his non-inertial twin Rob accelerating and making measurements in a stationary cavity. We find that these scenarios can be distinguished in the non-relativistic regime only by measurements on highly excited massive fields, allowing one to detect non-inertialness of the reference frame.

If nonlocality is to be inferred from a violation of a Bell inequality, an important assumption is that the measurement settings are freely chosen by the observers, or alternatively, that they are random and uncorrelated with the hypothetical local variables. I will examine the case where this assumption is weakened, so that measurement settings and local variables are at least partially correlated. It turns out that there is a connection between this type of model and models which reproduce nonlocal correlations by allowing classical communication between the distant parties. Exploiting this connection, I show that, with Bob's choice completely independent, if the correlation between Alice's choice and the local variables is just a single bit (of mutual information), then all correlations obtained from projective measurements on a singlet can be reproduced by local means.

Complex networks are structurally disordered systems that often display clustering behavior. The emergent clusters, also known as communities, consist of nodes that are more connected among themselves than they are connected with the rest of the network. Analyzing community structure is an important problem in network theory, with numerous applications in different fields. In this talk I explain how the evolution of a continuous-time quantum random walk on a complex network can be used to perform community detection.

A proposal for singlet-triplet spin measurement is introduced through exploiting the non-dissipative dynamics of a pair of electrons in a large square quantum dot followed by a single charge detection. It is shown that this may be used for entanglement swapping and teleportation. The method is also used to generate the AKLT ground state, a further resource for quantum computation. We justify, and derive analytic results for, an effective charge-spin Hamiltonian which is valid over a wide range of parameters and agrees well with exact numerical results of a realistic effective-mass model. Our analysis also indicates that the method is robust to choice of dot-size and initialization errors, as well as decoherence introduced by the hyperfine interaction.