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!

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.

Where Next?

Popular Pragmatic Bookshelf topics Top

yulkin
your book suggests to use Image.toByteData() to convert image to bytes, however I get the following error: "the getter ‘toByteData’ isn’t...
New
jamis
The following is cross-posted from the original Ray Tracer Challenge forum, from a post by garfieldnate. I’m cross-posting it so that the...
New
raul
Page 28: It implements io.ReaderAt on the store type. Sorry if it’s a dumb question but was the io.ReaderAt supposed to be io.ReadAt? ...
New
cro
I am working on the “Your Turn” for chapter one and building out the restart button talked about on page 27. It recommends looking into ...
New
jskubick
I think I might have found a problem involving SwitchCompat, thumbTint, and trackTint. As entered, the SwitchCompat changes color to hol...
New
adamwoolhether
I’m not quite sure what’s going on here, but I’m unable to have to containers successfully complete the Readiness/Liveness checks. I’m im...
New
brunogirin
When I run the coverage example to report on missing lines, I get: pytest --cov=cards --report=term-missing ch7 ERROR: usage: pytest [op...
New
brunogirin
When installing Cards as an editable package, I get the following error: ERROR: File “setup.py” not found. Directory cannot be installe...
New
andreheijstek
After running /bin/setup, the first error was: The foreman' command exists in these Ruby versions: That was easy to fix: gem install fore...
New
New

Other popular topics Top

AstonJ
What chair do you have while working… and why? Is there a ‘best’ type of chair or working position for developers?
New
DevotionGeo
I know that -t flag is used along with -i flag for getting an interactive shell. But I cannot digest what the man page for docker run com...
New
Rainer
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...
New
AstonJ
I’ve been hearing quite a lot of comments relating to the sound of a keyboard, with one of the most desirable of these called ‘thock’, he...
New
AstonJ
I have seen the keycaps I want - they are due for a group-buy this week but won’t be delivered until October next year!!! :rofl: The Ser...
New
dimitarvp
Small essay with thoughts on macOS vs. Linux: I know @Exadra37 is just waiting around the corner to scream at me “I TOLD YOU SO!!!” but I...
New
mafinar
This is going to be a long an frequently posted thread. While talking to a friend of mine who has taken data structure and algorithm cou...
New
First poster: bot
zig/http.zig at 7cf2cbb33ef34c1d211135f56d30fe23b6cacd42 · ziglang/zig. General-purpose programming language and toolchain for maintaini...
New
PragmaticBookshelf
Develop, deploy, and debug BEAM applications using BEAMOps: a new paradigm that focuses on scalability, fault tolerance, and owning each ...
New
AstonJ
If you’re getting errors like this: psql: error: connection to server on socket “/tmp/.s.PGSQL.5432” failed: No such file or directory ...
New

Sub Categories: