Research Interests

Characterising Quantum Phenomena

One of the most striking discoveries of last century is that Nature is incompatible with classical physics. Nonlocality [1], Contextuality [2] and Steering [3,4] are manifestations of powerful correlations which cannot be explained in the classical world, although they arise naturally in quantum mechanics. Quantum theory, however, does not exploit these phenomena to their maximum, i.e. even stronger correlations are theoretically conceivable while still complying with special relativity [5]. My research pursues an understanding of which nonclassical properties Nature may display, and how quantum theory features them.

A theory beyond Quantum

Quantum theory is currently our most accurate description of Nature, at least in the microscopic scale. Nevertheless, whether quantum theory is the ultimate theory of Nature remains unclear. One of the main reasons for this is the tension it displays with the theory of General Relativity. Indeed, both theories differ in crucial fundamental aspects, such as the role of “time”. Traditional approaches to resolving this tension, such as String Theory, have preserved the structure of quantum theory whilst modifying General Relativity [6]. However, recent insight has suggested the need to radically modify both theories [7]. Hence, quantum theory, and with it its applications, cannot be taken for granted, and it is therefore imperative that we explore the possibilities beyond it. My research seeks answers to how sensible deviations of quantum theory would look like, which nonclassical features they may have, and how nonquantum they may be, all within the promising framework of process theories [8].

Harnessing nonclassicality for information processing

Nonclassical features of quantum theory are known to enable information processing beyond our classical capabilities. Some have been explored in depth, such as the case of nonlocal correlations in Bell scenarios, which power secure quantum cryptography [9]. Other phenomena have only been recently explored, as is the case of Steering and Contextuality. Steering, for instance, enables a quantum advantage in semi-device-independent paradigms of quantum cryptography [10]. Contextuality, on the other hand, may power Measurement Based Quantum Computing [11,12], and is a necessary resource for universal quantum computation via magic state distillation [13]. My research aims at understanding and harnessing nonclassicality as a resource: how nonclassical properties of Nature, featured by quantum theory, may power technologies beyond what’s classically possible.

Nonclassicality in the macroscopic realm

A fundamental problem is to understand how classicality emerges from quantum theory in the macroscopic world. An aspect of this open question is that of witnessing nonclassicaliy in many-body systems, where the number of constituents may be arbitrarily large. This in turn is of particular interest when thinking of nonclassical systems as scalable resources for information processing [14]. My research explores how to certify nonclassicality in many-body systems from the information accessible via our current experimental capabilities.


References


[1] J. S. Bell, Physics 1:195200 (1964).[2] S. Kochen and E. P. Specker, J. Math. Mech. 17:5987 (1967).[3] E. Schrödinger, Mathematical Proceedings of the Cambridge Philosophical Society 32:446452 (1936). [4] H. M. Wiseman, S. J. Jones, and A. C. Doherty, Phys. Rev. Lett. 98:140402 (2007).[5] S. Popescu and D. Rohrlich, Found. Phys. 24:379 (1994).[6] J. Polchinski, “String theory”. C. U. Press, 1998. [7] L. Hardy, J. Phys. A 40, 3081 (2007).[8] B. Coecke and A. Kissinger. Picturing Quantum Processes: A First Course in Quantum Theory and Diagrammatic Reasoning. CUP, 2017.[9] N. Brunner et al. Rev. Mod. Phys., 86:419, 2014.[10] D Cavalcanti and P Skrzypczyk. Rep. Prog. Phys., 80:024001, 2017.[11] J. Anders and D. E. Browne. Phys. Rev. Lett., 102:050502, 2009.[12] R. Raussendorf. Phys. Rev. A, 88:022322, 2013.[13] M. Howard et al. Nature, 510:351, 2014. [14] M. Lewenstein, A. Sanpera, and V. Ahufinger. Ultracold Atoms in Optical Lattices: Simulating quantum many-body systems. Oxford University Press, 2012.