Cassandra Granade cgranade

Operator Sum representation support for QuTiP

Abstract

When working with quantum objects in QuTiP, the library provides the concept of a kind, allowing the use of state vectors, dual vectors, density operators, unitary operators, and superoperators all in unified fashion. Currently, however, this support does not include representations of operator-sum decompositions of channels or instruments. For example, qt.to_kraus returns a list of Qobj instances, which then has no further metadata nor any way of enforcing that each consituent Qobj instance agrees in dimensions and other metadata. Similarly, instruments can commonly be represented by a decomposition into a sum of completely positive trace non-increasing channels, but there is no current reflection of this structure in QuTiP. This design document describes a modification to QuTiP to enable first-class support for operator-sum decompositions.

Dimensions

In general, QuTiP differentiates between kinds by using decompositions of array sh

DISCLAIMER: This post is still in a draft!

Falsehoods programmers believe about quantum computing

Preamble

Quantum computing has captured broad attention and fascination over the past few years, but with that interest has come a large number of well-intentioned misunderstandings. In this post, I'll lay out a few of these falsehoods in the tradition of other wonderful falsehood lists, and in the hopes of spurring more exploration into this new and fascinating way of solving hard problems.

As a brief housekeeping note, these falsehoods are ordered by theme and topic, not in order of complexity, so don't worry if some of these points seem a bit intimidating. If you're looking to learn more about quantum computing in the first place, check out Learn Quantum Computing with Python and Q# (Manning Publications, October 2020) by Sarah Kaiser and myself.

Special thanks to everyone that made

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	# ]

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	This is a terrible tool, make your peace with that first and foremost.

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	directory, makes HTML out of them by using a terrible template, then

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	# in particular the match statement.
	# If you get a syntax error, you may need a more
	# recent version of Python.
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	from dataclasses import dataclass

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	name: repo2docker-repro
	dependencies:
	- notebook
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	- numpy

	FROM mcr.microsoft.com/quantum/iqsharp-base:0.10.2002.2610
	ENV IQSHARP_HOSTING_ENV=dev-to-sckaiser-arrays

	# Make sure the contents of our repo are in ${HOME}.
	# These steps are required for use on mybinder.org.
	USER root
	COPY . ${HOME}
	RUN chown -R ${USER} ${HOME}

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