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 …
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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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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 …
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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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