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- Kamil Bradler, Patrick Hayden, Dave Touchette, Mark M. Wilde
- ArXiv
- 2010

Coding theorems in quantum Shannon theory express the ultimate rates at which a sender can transmit information over a noisy quantum channel. More often than not, the known formulas expressing these transmission rates are intractable, requiring an optimization over an infinite number of uses of the channel. Researchers have rarely found quantum channels… (More)

- Mario Berta, Matthias Christandl, Dave Touchette
- IEEE Transactions on Information Theory
- 2016

In quantum state redistribution as introduced by Luo and Devetak and Devetak and Yard, there are four systems of interest: the A system held by Alice; the B system held by Bob; the C system that is to be transmitted from Alice to Bob; and the R system that holds a purification of the state in the ABC registers. We give upper and lower bounds on the amount… (More)

- Dave Touchette
- ArXiv
- 2014

We define a new notion of information cost for quantum protocols, and a corresponding notion of quantum information complexity for bipartite quantum channels, and then investigate the properties of such quantities. These are the fully quantum generalizations of the analogous quantities for bipartite classical functions that have found many applications… (More)

- Dave Touchette
- STOC
- 2015

We define a new notion of information cost for quantum protocols, and a corresponding notion of quantum information complexity for bipartite quantum tasks. These are the fully quantum generalizations of the analogous quantities for bipartite classical tasks that have found many applications recently, in particular for proving communication complexity lower… (More)

- Mark Braverman, Ankit Garg, Young Kun-Ko, Jieming Mao, Dave Touchette
- 2015 IEEE 56th Annual Symposium on Foundations of…
- 2015

We prove a near optimal round-communication tradeoff for the two-party quantum communication complexity of disjointness. For protocols with r rounds, we prove a lower bound of Omega(n/r) on the communication required for computing disjointness of input size n, which is optimal up to logarithmic factors. The previous best lower bound was… (More)

- Gilles Brassard, Alain Tapp, Dave Touchette
- 2014 IEEE 55th Annual Symposium on Foundations of…
- 2014

We study the problem of simulating protocols in a quantum communication setting over noisy channels. This problem falls at the intersection of quantum information theory and quantum communication complexity, and will be of importance for eventual real-world applications of interactive quantum protocols, which can be proved to have exponentially lower… (More)

- Dave Touchette
- 2014

We present the first general direct sum theorem for quantum communication complexity that holds for more than a single round of communication. A direct sum theorem states that to compute n tasks simultaneously requires as much resources as the amount of the given resource required for computing them separately. By a general direct sum theorem, we mean a… (More)

- Mathieu Laurière, Dave Touchette
- ArXiv
- 2017

In the context of two-party interactive quantum communication protocols, we study a recently defined notion of quantum information cost (QIC), which possesses most of the important properties of its classical analogue, see Ref. [Tou15]. Notably, its link with amortized quantum communication complexity has been used in Ref. [BGKK + 15] to prove an (almost)… (More)

- Dave Touchette
- ArXiv
- 2014

We prove a direct sum theorem for bounded round entanglement-assisted quantum communication complexity. To do so, we use the fully quantum definition for information cost and complexity that we recently introduced, and use both the fact that information is a lower bound on communication, and the fact that a direct sum property holds for quantum information… (More)

- Anurag Anshu, Dave Touchette, Penghui Yao, Nengkun Yu
- ArXiv
- 2016

We exhibit a Boolean function for which the quantum communication complexity is exponentially larger than the classical information complexity. An exponential separation in the other direction was already known from the work of Kerenidis et. al. [SICOMP 44, pp. 1550–1572], hence our work implies that these two complexity measures are incomparable. As… (More)