# Linked Questions

33 questions linked to/from Understanding the Bloch sphere
2 votes
3 answers
436 views

### Prove that qubits can be represented on a unit sphere, avoiding the density matrix formalism [duplicate]

The Bloch Sphere is regarded as the most "intuitive" way of explaining a 2-level quantum system in computation and rotations of states described on Bloch sphere provides a really easy ...
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3 votes
1 answer
548 views

### What is the physical intuition for Bloch Sphere? [duplicate]

I am very confused about how to think about the Bloch Sphere. How can we relate the concept of expectation value to the Bloch sphere? If my state lies in let's say $yz$ plane how can we say that ...
1 vote
0 answers
225 views

### Do Bloch sphere rotations span $SU(2)$ (up to a global phase)? [duplicate]

It is well known that the Pauli group $\{I,X,Y,Z\}$ spans the group of $2\times2$ unitary matrices, $SU(2)$, for example see this link. A general Bloch sphere rotation by an angle $\alpha$ about an ...
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15 votes
3 answers
3k views

### Up and down spin are orthogonal, not antiparallel

In conventional coordinate systems (anything you solve a simple Newtonian mechanics problem with), up and down are + and - z. A vector pointing up and a vector pointing down are anti-parallel. But in ...
• 227
5 votes
2 answers
849 views

### Components of electron spin towards three dimensional coordinate axes

The electron spin can be described using two orthonormal state vectors in two dimensional Hilbert space. If we assume the two orthonormal vectors as $|+\rangle$ and $|-\rangle$, we can represent the ...
• 378
5 votes
3 answers
4k views

### How are quantum qubits implemented?

Its very easy to pull a logic gate or transistor circuit of the internet for example and begin to understand how it represents physical bits, by either having 5V across the circuit or below 3.3V. But ...
6 votes
5 answers
2k views

### Interpretation of rotating a quantum state

I'm currently taking an introductory quantum mechanics course, where the last covered topic was spin and identical particles. During some reading online, I stumbled across the term "rotating a quantum ...
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1 vote
3 answers
2k views

• 158
3 votes
4 answers
1k views

0 votes
1 answer
1k views

I'm trying to work through a problem that wants me to determine the Bloch sphere representation of the eigenvectors of $\sigma_{z}$. I'm working in bra-ket notation so these would be $\ v_{+} = |0\... 2 votes 3 answers 263 views ### Quantum Mechanics Notation I'm studying the Bloch Sphere and just wanted to ask what this notation means:$|\psi\rangle = \alpha|1\rangle$for example I'm just not familiar with the notation in this context if anyone could ... 1 vote 1 answer 1k views ### Projection of spin I have a naive and stupid question. In university we learn that particles, i.e. electrons have spin$1/2$. This spin can have 2 projections on some axis that we chose with the values$1/2$and$-1/2$. ... 1 vote 1 answer 463 views ### Is the Bloch sphere a bad way to visualize a qubit? When a qubits is in a quantum state it can be measured as$[0\rangle$or$[1\rangle\$. Then why does the Bloch sphere have these two states on antipodal sides of the spheres? If I want to plot the ...
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