Quantum foundations, quantum information theory and quantum cryptography
单位：University of Cambridge
研究方向：Quantum foundations, quantum information theory and quantum cryptography
* the relationships between fundamental principles of quantum theory and other physical theories and information theoretic tasks. One class of examples are quantum key distribution schemes, begining with the so-called BHK protocol -- the first secure quantum key distribution scheme based on the no-signalling principle -- which Jonathan Barrett, Lucien Hardy and I devised. More recently, Jonathan Barrett, Roger Colbeck and I invented an unconditionally secure device-independent quantum key distribution scheme that requires only two devices and whose security can be proved from the
no-signalling principle. Another class of examples, from 2011-2, includes solutions to a longstanding cryptographic problem -- finding a simple and provably unconditionally secure scheme for bit commitment -- that relies essentially on the properties of quantum information in Minkowski space.
* the quantum reality problem, and specifically finding theories that respect special relativity and quantum theory and that also supply an explicitly realist ontology.
* the physics of decoherence and its implications for fundamental physics
* novel tests of quantum theory and alternative theories
* new cryptographic applications of quantum information
* other novel scientific applications of quantum information.
I co-edited "Many Worlds? Everett, Quantum Theory and Reality" (Oxford University Press, 2010). My chapter in the book critically reviews recent attempts to make sense of many-worlds quantum theory, and in particular to make sense of probability within many-worlds quantum theory -- which we clearly need to do if the theory is to reproduce all the probabilistic predictions of standard quantum theory, but which is also clearly (at best) problematic, since many-worlds quantum theory is deterministic. I argue in particular that we can (despite the claims of many Everettians) find a satisfactory account of the scientific treatment of one-world theories involving apparently random data, and that there is no satisfactory parallel treatment of many-worlds theories. I also point out some (I think insuperable) problems with recent attempts to describe how many-worlds theories can be confirmed or disconfirmed by evidence. And I explain why the attempt to reinterpret the Born weights as some form of "caring measure" in Everettian quantum theory aren't rationally compelling.