# I Quantum Computing

#### MrMuscle

Summary
How can I write the vector notation of quantum states when I have a 2 qubit system?
I am confused about the vector notation of quantum states when I have a 2 qubit system.

For 1 qubit, I just write l1> = (0 ;1 ) for representing 1,

and l0> = (1;0) for representing 0.

Dirac notation is straightforward
However when it comes to representing two qubits in linear algebra I am confused :(

What is the vector notations for the following ones? Can you suggest a method to calculate them I don't want to memorize.

l00> = ?
l11>= ?
l10>= ?
l01>= ?

Thanks in advance!

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#### Mentz114

Gold Member
Summary: How can I write the vector notation of quantum states when I have a 2 qubit system?

I am confused about the vector notation of quantum states when I have a 2 qubit system.

For 1 qubit, I just write l1> = (0 ;1 ) for representing 1,

and l0> = (1;0) for representing 0.

Dirac notation is straightforward
However when it comes to representing two qubits in linear algebra I am confused :(

What is the vector notations for the following ones? Can you suggest a method to calculate them I don't want to memorize.

l00> = ?
l11>= ?
l10>= ?
l01>= ?

Thanks in advance!
What you are doing is making a tensor product of two vector spaces, each of dimension 2. Read the first part of this
or may be this is clearer

• atyy

#### atyy

Science Advisor
Here are some more links in addition to those above from @Mentz114.

• Mentz114

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