.. title: Quantum Class 21, Mon 2022-11-28
.. slug: class21
.. date: 2022-11-27
.. tags: class
.. category:
.. link:
.. description:
.. type: text
.. has_math: true
.. sectnum::
.. contents:: Table of contents
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..
Quantum jokes
=============
of varying quality... https://upjoke.com/quantum-jokes
Final project presentations
===========================
#. Everyone who requested a specific date, got it. I assigned the others to even out the calendar.
#. Do any of the Dec 1 people want to move to Dec 5? The first two who email me can do that.
#. Other changes that don't overload particular days might be ok.
#. No matter when you talk, you have until Fri Dec 9 to submit your project.
Final project presentations
===========================
#. Everyone who requested a specific date, got it. I assigned the others to even out the calendar.
#. Do any of the Dec 1 people want to move to Dec 5? The first two who email me can do that.
#. Other changes that don't overload particular days might be ok.
#. No matter when you talk, you have until Fri Dec 9 to submit your project.
#. Updated list is on class 22.
Jochen Rao on Molecules
=======================
#. This fits together with the variational quantum eigensolver talk.
#. `22.Molecules `_ 9:50 Dec 11, 2020
Measurement-based computation, aka One way quantum computation
==============================================================
This is an alternative to the `quantum logic gate model `_ that uses reversible unitary gates in a quantum circuit.
Since performing a measurement changes the measured qbits, use it.
#. https://www.quantiki.org/wiki/one-way-computation :
"One way quantum computation (1WQC) uses an initially highly entangled state (called a cluster state), and then a pattern of single qubit measurements along different directions, together with feed-forward based on the results, in order to drive a quantum computation. The final result of the computation is obtained by measuring the last remaining qubits in the computational basis..."
#. https://en.wikipedia.org/wiki/One-way_quantum_computer
a. This is a one-way computer.
b. Operations:
i. Supplement the input/output qbits with some auxillary qbits.
#. Entangle some of them.
#. Measure some of the auxillary qbits wrt some bases. This affects the output qbits since they are entangled.
#. Depending on the measurement results, perform further operations on the output qbits. These are called corrections.
#. Repeat.
#. This has equivalent formal power to reversible gates.
#. It may be better suited to certain HW.
#. `One-way Quantum Computation - a tutorial introduction `_ Dan E. Browne, Hans J. Briegel.
#. How the excellent Jochen Rau presents it:
`14. Measurement-based computation `_ 36:44. Nov 27, 2020
#. So now you've seen 3 models of quantum computation.
MaxCut
======
https://en.wikipedia.org/wiki/Maximum_cut
Rao again, since he's excellent.
`21.Classical optimization: MaxCut problem `_ 14:47