Former and current IQOQI-Vienna scientists Igor Pikovski, Magdalena Zych, Fabio Costa and Časlav Brukner[1] explored the effect of time dilation in quantum systems and decoherence and critically analyzed the effect in view of the description in different reference frames, the role of the equivalence principle and the effective irreversibility of the decoherence. This work brought clarity to several aspects of the physics of quantum phenomena and general relativistic effects, two regimes with different traditions.

In an independent work[2], a group of Austrian researchers including IQOQI-Vienna scientist Časlav Brukner used a 5-path interferometer to obtain tight bounds on higher-order interferences. Since higher order interferences can only exist in generalized probabilistic theories – experiments searching for such higher interferences are used to distinguish between quantum mechanics and more general theories. With the result, previous bounds were refined by two orders of magnitude.

IQOQI-Vienna’s Nicolai Friis is the first author of our third highlight[3]. Together with researchers from Innsbruck, Barcelona (Spain) and Konstanz (Germany), he exploited the quadratic advantage quantum metrology offers over classical approaches to parameter estimation problems, overcoming the hurdle of actually implementing the required quantum probe states and measurements by introducing a resource that will prove helpful for numerous future research efforts in this area: the flexible 2D cluster states, which are useful for efficient sensing and measurement operations.

[1]                Time dilation in quantum systems and decoherence

                  Igor Pikovski et al 2017 New J. Phys. 19 025011

[2]                Obtaining tight bounds on higher-order interferences with a 5-path interferometer
                  Thomas Kauten et al 2017 New J. Phys. 19 033017

[3]                Flexible resources for quantum metrology

                  Nicolai Friis et al 2017 New J. Phys. 19 063044