Peter,

Did you get my earlier e-mail about possibly

giving a talk on Mon., Nov. 20 on additivity

violations??

See below.

If not, I'd be happy to meet informally with

anyone interested either Mon. afternoon

or Tues. morning Nov. 21.

Beth

On Thu, Nov 9, 2017 at 9:52 PM, Peter Shor <shor@math.mit.edu> wrote:

It's Veteran's Day.

Anybody who wants to talk next week please email me.

Thanks,

Peter
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---------- Forwarded message ----------
From: Beth Ruskai <mbruskai@gmail.com>
Date: Mon, Nov 6, 2017 at 9:04 AM
Subject: special seminar
To: Isaac Chuang <ichuang@mit.edu>, Peter Shor <shor@math.mit.edu>
Cc: slloyd@mit.edu, aram harrow <aram@mit.edu>

Dear Peter, Aram, Ike and Seth,

I will be in the Boston area Nov. 20 and 21 and

wonder if they would be any interest in -- and

enough people around -- for a special seminar

on the topic below.

My current plan is to fly in Mon. morning on

an early flight. So Mon. afternoon would

work best for me. However, late Mon.

morning would also work. Tues. morning I

am free, but would need to leave by noon.

Beth

Title: Using local additivity to find examples of superadditivity of quantum channels.

Speaker: Mary Beth Ruskai

Abstract: The local additivity of minimal output entropy can be extended to local additivity of maximal relative entropy with respect to a fixed reference state. This can be exploited to test channels for superadditivity of Holevo capacity with numerical effort comparable to searching for the minimal output entropy. Local maxima which do not arise from product inputs play a key role. Moreover, evidence of superadditivity can be found even if the additivity violation itself is too small to be seen numerically.

This talk will be divided into two parts. First we sketch the Gour-Friedland proof of local additivity with several significant simplifications.

Second, we describe a program to test 3-state qubit channels for superadditivity of the Holevo capacity.

*****************************************************************************

Mary Beth Ruskai ruskai@member.ams.org

710 Wake Robin Dr. mruskai@uvm.edu

Shelburne, VT 05482 http://mbruskai.info/

cell +1 802 829 0085 text OK, but no voice mail:

internet +1 802 489 4954 can get messages.

Emeritus Professor of Mathematics, University of Massachusetts Lowell

Research Professor, Tufts University (2003-2013)

Associate Member, Institute for Quantum Computing, Waterloo, Canada (2012-2016)

Research Affiliate, University of Vermont