June 2017 - ITP-quantumseminare - lists.phys.ethz.ch

Tomorrow's group meeting E41.1 @ 4pm
by Joe Renes 25 Jun '17

25 Jun '17

Hi all, This week we have several visitors, and tomorrow we'll hear from John de Brota from University of Massachusetts Boston. His title and abstract are attached below. Best, Joe Title: "Why the MIC Shall Inherit the Earth: From QBism to Minimal Informationally Complete Quantum Measurements" Abstract: There have been many information-flavored reconstructions of quantum theory. Common wisdom advises that these reconstructions be “interpretation independent.” Possibly as a consequence of this agnosticism, however, we are left with reconstructions that, at least to some, do not suggest much about the nature of reality. We discuss an attempt to reconstruct quantum theory explicitly from QBist principles. QBism deems all probabilities in quantum theory to be subjective Bayesian degrees of belief. Taking this perspective seriously implies that the Born rule is a normative relation between hypothetical measurements an agent may consider. In the reconstruction, this property appears as a structural analog of the law of total probability, thereby directly reflecting the point of view that quantum theory is an empirical addition to coherence. The explicit form of this relation is not unique, relying instead on the choice of a minimal informationally complete (MIC) quantum measurement. A SIC-POVM has been chosen in the past mostly on aesthetic grounds, but which MIC-POVM we choose stands a chance of revealing or obscuring the properties which probability distributions equivalent to quantum states must have. To make an informed choice, we must learn as much as we can about the space of MIC-POVMs. In this talk I will elaborate these motivations and prove several properties about MIC-POVMs.

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Visitor 29th June
by Sandra Rankovic 21 Jun '17

21 Jun '17

Dear all, Vikesh Siddhu from Bob Griffiths group is visiting next Thursday, 29th. He would like to give an informal talk, so lets meet at 3pm in front of Renato's office (we'll move if this place is taken). Please let me know if this time is not good. He is mainly visiting to meet people in the group, he stays only one day so please spare some time to tell him what you do if possible. Here is the abstract he sent: Title: Some qutrit channels with application to additivity of quantum capacity. Abstract Understanding quantum communication capacity of noisy quantum channels is a central issue in qauntum information theory. One big challenge is posed by non-additivity of the quantum capacity. A quantum channel has an associated isometry that maps the input to the output and environment. We introduce a simple class of channels called pcubed, for which the channel isometry maps a basis (generally non-orthogonal) of pure states at the input to pure states at the output. Degradable channels are of interest because their one-shot quantum capacity is additive and equals the quantum capacity. Pcubed isometries can be used to produce a variety of degradable and non-degradable channels. We have studied a two parameter family of pcubed qutrit channels which show interesting behaviour. Two such channels in parallel can exhibit either additive or non-additive behaviour of the one-shot quantum capacity. Best, Sandra

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no meeting today
by Joe Renes 19 Jun '17

19 Jun '17

instead: https://foundations.ethz.ch/ Best, -joe

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no meeting today
by Joe Renes 12 Jun '17

12 Jun '17

Hi all, sorry for the late notice (the semester ends and there goes your brain) --- no meeting today. -joe

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