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- Robert W. Spekkens, Terry Rudolph
- Quantum Information & Computation
- 2002

Received (received date) Revised (revised date) It is well known that no quantum bit commitment protocol is unconditionally secure. Nonetheless, there can be non-trivial upper bounds on both Bob's probability of correctly estimating Alice's commitment and Alice's probability of successfully unveiling whatever bit she desires. In this paper, we seek to… (More)

A controversy that has arisen many times over in disparate contexts is whether quantum co-herences between eigenstates of certain quantities are fact or fiction. We present a pedagogical introduction to the debate in the form of a hypothetical dialogue between proponents from each of the two camps: a factist and a fictionist. A resolution of the debate can… (More)

Recently, there has been much interest in a new kind of " unspeakable " quantum information that stands to regular quantum information in the same way that a direction in space or a moment in time stands to a classical bit string: the former can only be encoded using particular degrees of freedom while the latter are indifferent to the physical nature of… (More)

- Bob Coecke, Bill Edwards, Robert W. Spekkens
- Electr. Notes Theor. Comput. Sci.
- 2011

- Stephen D Bartlett, Terry Rudolph, Robert W Spekkens
- Physical review letters
- 2003

We show that communication without a shared reference frame is possible using entangled states. Both classical and quantum information can be communicated with perfect fidelity without a shared reference frame at a rate that asymptotically approaches one classical bit or one encoded qubit per transmitted qubit. We present an optical scheme to communicate… (More)

- Bob Coecke, Robert W. Spekkens
- Synthese
- 2012

We introduce a graphical framework for Bayesian inference that is sufficiently general to accommodate not just the standard case but also recent proposals for a theory of quantum Bayesian inference wherein one considers mixed quantum states rather than probability distributions as representative of degrees of belief. The diagrammatic framework is stated in… (More)

- Iman Marvian, Robert W Spekkens
- Nature communications
- 2014

Noether's theorem is a fundamental result in physics stating that every symmetry of the dynamics implies a conservation law. It is, however, deficient in several respects: for one, it is not applicable to dynamics wherein the system interacts with an environment; furthermore, even in the case where the system is isolated, if the quantum state is mixed then… (More)

- Bob Coecke, Tobias Fritz, Robert W. Spekkens
- Inf. Comput.
- 2016

In many different fields of science, it is useful to characterize physical states and processes as resources. Chemistry , thermodynamics, Shannon's theory of communication channels, and the theory of quantum entanglement are prominent examples. Questions addressed by a theory of resources include: Which resources can be converted into which other ones? What… (More)

Extended abstract for the article " A quantum advantage for inferring causal structure " , Nature Physics (2015) [9]. Causal explanations are a singularly useful way of organizing one's knowledge about the world. This has long been recognized by philosophers and, in recent decades, motivated the development of a rigorous mathematical framework, which proved… (More)

- Ravi Kunjwal, Robert W Spekkens
- Physical review letters
- 2015

The Kochen-Specker theorem demonstrates that it is not possible to reproduce the predictions of quantum theory in terms of a hidden variable model where the hidden variables assign a value to every projector deterministically and noncontextually. A noncontextual value assignment to a projector is one that does not depend on which other projectors-the… (More)