PragProg Customers

Quantum Computing: Bra and ket (p. 187)

NiklasH

NiklasH

Quantum Computing: Bra and ket (p. 187)

On page 187 in section “Can the Quantum Gate Matrix Be Anything?”, psi-dagger is defined as <psi^dagger| = (w0* w1*).

As per my understanding, the conjugate transpose of a bra is actually the ket, meaning <psi^dagger| = |psi> with |psi> being a column vector with entries w0 and w1 (not w0* and w1*). Am I missing something here?

(Also quoting Wikipedia here, section “Bras and kets as row and column vectors” in https://en.wikipedia.org/wiki/Bra–ket_notation: “The conjugate transpose (also called Hermitian conjugate) of a bra is the corresponding ket and vice versa”)

Thank you very much for any clarification on this topic!

1 comment
/book-quantum-computing
0 743 1

First Post!

nihal.mehta

nihal.mehta

Author of Quantum Computing

You are right that the bra and kets are conjugate transpose (or Hermitian conjugates) of each other. So, if |psi> is a column vector whose elements are w0 and w1, then <psi^dagger| is the row vector whose elements are w0* and w1* as shown on the bottom of page 187. That is, |psi>^dagger = <psi^dagger|.
The math notation can sometimes seem confusing. So, it’s best to understand the intent of what’s going on and then the notation will follow. Also, using actual numbers instead
of letters may help to clarify.

Post #2

Where Next?

View thread on forum
View Quantum Computing's book portal
Post errata for this book
Post a suggestion for this book
Post a question about this book
Post a review about this book
Home PragProg Customers
/book-quantum-computing
0 743 1
Last post

Popular Pragmatic Bookshelf topics Top

jimschubert
PragProg Customers

Distributed Services With Go - Ch 3 index errors on Config
In Chapter 3, the source for index introduces Config on page 31, followed by more code including tests; Config isn’t introduced until pag...
#pragprog#errata/book-distributed-services-with-go
8 1316 3
New
johnp
PragProg Customers

Python Testing with pytest - Chapter 5 example c AttributeError: 'module' object has no attribute 'config'
Running the examples in chapter 5 c under pytest 5.4.1 causes an AttributeError: ‘module’ object has no attribute ‘config’. In particula...
#errata/book-python-testing-with-pytest
5 3582 1
New
gilesdotcodes
PragProg Customers

Modern CSS with Tailwind: setting up Rails app
In case this helps anyone, I’ve had issues setting up the rails source code. Here were the solutions: In Gemfile, change gem 'rails' t...
#errata/book-modern-css-with-tailwind
3 1278 2
New
brian-m-ops
PragProg Customers

Python Testing with pytest, Second Edition: cards pip install error (page 12)
#book-python-testing-with-pytest-second-edition Hi. Thanks for writing the book. I am just learning so this might just of been an issue ...
#errata/book-python-testing-with-pytest-second-edition
4 1191 3
New
patoncrispy
PragProg Customers

Hands-on Rust: Adequate docs for bracket_lib
I’m new to Rust and am using this book to learn more as well as to feed my interest in game dev. I’ve just finished the flappy dragon exa...
#question/book-hands-on-rust
5 1516 3
New
jgchristopher
PragProg Customers

Programming Phoenix LiveView: live_modal/2 instead of live_component/3 (210)
“The ProductLive.Index template calls a helper function, live_component/3, that in turn calls on the modal component. ” Excerpt From: Br...
#errata/book-programming-phoenix-liveview
3 1042 6
New
Charles
PragProg Customers

Programming Phoenix LiveView: book not updated to version 1.6 (p. 18)
In general, the book isn’t yet updated for Phoenix version 1.6. On page 18 of the book, the authors indicate that an auto generated of ro...
#errata/book-programming-phoenix-liveview
9 2051 12
New
brunogirin
PragProg Customers

Python Testing with pytest, Second Edition: error when installing editable package (page 178)
When installing Cards as an editable package, I get the following error: ERROR: File “setup.py” not found. Directory cannot be installe...
#errata/book-python-testing-with-pytest-second-edition
0 1739 1
New
kevinjyh
PragProg Customers

Python Testing with pytest, Second Edition:Abou epub format
Is the book’s epub format available to read on Google Play Books?
#question/book-python-testing-with-pytest-second-edition
0 1126 3
New
mert
PragProg Customers

Agile Web Development with Rails 7: page 152, page 153:
AWDWR 7, page 152, page 153: Hello everyone, I’m a little bit lost on the hotwire part. I didn’t fully understand it. On page 152 @rub...
#question/book-agile-web-development-with-rails-7
0 1230 4
New

Other popular topics Top

brentjanderson
General Dev>Hardware

Moonlander Keyboard (Mechanical) (Ergonomic) (Split) (Ortholinear)
Bought the Moonlander mechanical keyboard. Cherry Brown MX switches. Arms and wrists have been hurting enough that it’s time I did someth...
#hardware/keyboards#moonlander#mechanical-keyboards#ortholinear#ergonomic
212 17779 90
New
Rainer
Community>Journals

Programming Erlang Book Club
My first contact with Erlang was about 2 years ago when I used RabbitMQ, which is written in Erlang, for my job. This made me curious and...
/erlang/book-programming-erlang-2nd-edition#book-club
195 6815 95
New
AstonJ
General Dev>Hardware

Poll: Which keyboard layout do you use?
poll poll Be sure to check out @Dusty’s article posted here: An Introduction to Alternative Keyboard Layouts It’s one of the best write-...
colemakmods.github.io
#polls/keyboards
10 6048 11
New
AnfaengerAlex
Android>Questions

Unresolved Reference to android in build.gradle.kts – Beginner Issue
Hello, I’m a beginner in Android development and I’m facing an issue with my project setup. In my build.gradle.kts file, I have the foll...
#binding
0 7460 2
New
PragmaticBookshelf
Backend>Learning Resources

Ash Framework
Explore the power of Ash Framework by modeling and building the domain for a real-world web application. Rebecca Le @sevenseacat and ...
pragprog.com
#pragprog/elixir#published-book/ash/book-ash-framework
15 7555 9
New
PragmaticBookshelf
Backend>Learning Resources

The Art of Functional Programming
A masterclass in the fundamentals and principles of functional programming. Minh Quang Tran The Art of Functional Programming is a ma...
pragprog.com
#pragprog/haskell/java#published-book/book-the-art-of-functional-programming
2 9360 1
New
AstonJ
AI>Chat

Post your DeepSeek results
Curious what kind of results others are getting, I think actually prefer the 7B model to the 32B model, not only is it faster but the qua...
/deepseek
15 4275 15
New
RobertRichards
Game Dev>Chat

Hair Salon Games for Girls Fun
Hair Salon Games for Girls Fun Girls Hair Saloon game is mainly developed for kids. This game allows users to select virtual avatars to ...
#ios#android#unity#fun
2 3556 1
New
PragmaticBookshelf
Backend>Learning Resources

Eloquent Ruby, Second Edition
Write elegant Ruby code—not just correct, but idiomatic. Go beyond the vocabulary and syntax and learn to express yourself with eloquence...
pragprog.com
#pragprog/ruby#published-book/book-eloquent-ruby-second-edition
11 7668 8
New
CommunityNews
Game Dev>In The News

Grand Theft Auto: Vice City | DOS games in browser
Open-source implementation of the classic GTA engine now running directly in your browser. Experience the reVC technology demo on DOS.Zon...
dos.zone
#games#browser
0 173 0
New
Back to top

Latest in Quantum Computing

Quantum Computing Portal ❯

PragProg Customers

Pragmatic Bookshelf PragProg Customers ❯

Latest on Devtalk

Devtalk ❯

We ❤️ helpful members!

We reward our most helpful members via our MOTM scheme - by giving away a whopping 25 books per year!

Member of the Month

Devtalk Sponsors

Pragmatic Bookshelf

Practical resources that improve the lives of professional developers.

Erlang Solutions

We build trusted fault-tolerant systems that scale to billions of users.

Honeybadger

Real-time error tracking, performance insights, and observability for devs.

EEF

Supporting innovation across the BEAM ecosystem.

coders51

We build reliable cloud platforms for business-critical systems.

Manning Publications

Develop your skills with books, videos, and courses.

AppSignal

Catch errors, track performance, monitor hosts and more.

WyeWorks

Enabling companies to succeed by building software people love.

Pragmatic Studio

Courses that move you from confusion to "Aha, now I get it!"

Linux New Media

Publishing Linux Magazine, ADMIN, and MakerSpace for 25+ years.

View all our sponsors ❯

Categories:

Sub Categories:

Popular Portals

Devtalk Sponsors

Pragmatic Bookshelf

Practical resources that improve the lives of professional developers.

Erlang Solutions

We build trusted fault-tolerant systems that scale to billions of users.

Honeybadger

Real-time error tracking, performance insights, and observability for devs.

EEF

Supporting innovation across the BEAM ecosystem.

coders51

We build reliable cloud platforms for business-critical systems.

Manning Publications

Develop your skills with books, videos, and courses.

AppSignal

Catch errors, track performance, monitor hosts and more.

WyeWorks

Enabling companies to succeed by building software people love.

Pragmatic Studio

Courses that move you from confusion to "Aha, now I get it!"

Linux New Media

Publishing Linux Magazine, ADMIN, and MakerSpace for 25+ years.

View all our sponsors ❯

We're in Beta

About us Mission Statement See our Roadmap