Bounding Temporal Quantum Correlations

Bounding the set of quantum correlations.

We introduce a hierarchy of conditions necessarily satisfied by any distribution P_{alphabeta} representing the probabilities for two separate observers to obtain outcomes alpha and beta when making local measurements on a shared quantum state. Each condition in this hierarchy is formulated as a semidefinite program. Among other applications, our approach can be used to obtain upper bounds on t...

Observation of local temporal correlations in trapped quantum gases.

We measure the temporal pair correlation function g(2)(τ) of a trapped gas of bosons above and below the critical temperature for Bose-Einstein condensation. The measurement is performed in situ by using a local, time-resolved single-atom sensitive probing technique. Third- and fourth-order correlation functions are also extracted. We develop a theoretical model and compare it with our experime...

Towards Quantum Distance Bounding Protocols

Distance Bounding (DB) is a security technique through which it is possible to determine an upper-bound on the physical distance between two parties (denoted as verifier and prover). These protocols typically combine physical properties of the communication channel with cryptographic challenge-response schemes. A key challenge to design secure DB protocols is to keep the time required by the pr...

Nonclassicality of Temporal Correlations.

The results of spacelike separated measurements are independent of distant measurement settings, a property one might call two-way no-signaling. In contrast, timelike separated measurements are only one-way no-signaling since the past is independent of the future but not vice versa. For this reason some temporal correlations that are formally identical to nonclassical spatial correlations can s...

Bounding the quantum dimension with contextuality