Tag: projection-operator

7 Confusion regarding projection operator 2018-06-09T10:00:22.750

7 Quantum channel representation of projective measurement 2019-06-13T00:57:22.930

7 What can I conclude about $\langle \phi|\pi_1\pi_2|\phi\rangle$ if $\langle \phi|\pi_i|\phi\rangle\ge e$? 2020-11-17T17:06:58.183

6 Error syndromes and recovery procedure in bit flip code 2019-06-07T21:39:40.613

6 Bob applies a projector - what happens to eigenvalues of Alice's reduced state? 2020-10-20T02:17:47.967

4 How do I prove that $P_\pm=\frac12(1\pm U)$ if $U^2=I$? 2020-12-16T23:47:48.107

4 Does $\frac{\Pi_A\otimes I_B}{\text{Tr}((\Pi_A\otimes I_B)\rho_{AB})}\rho_{AB}=\rho_{AB}$ hold for a state $\rho_{AB}$ and projector $\Pi_A$? 2021-02-23T07:16:32.580

3 Weeding out qubit states with leftmost qubit as 1 2019-06-10T14:56:39.183

3 Confusion about the relation between POVMs and projective measurements 2019-08-13T22:43:25.860

3 What does "measuring a state" mean? 2019-11-13T17:09:29.590

3 Implications of commuting within the code space 2019-11-26T21:29:27.417

3 Interpretation of specific Hamiltonian operator 2019-12-11T10:47:19.377

3 Quantum error correction using bit-flip code for the amplitude damping channel 2019-12-12T06:16:06.273

3 Help in understanding the usage of eigenvalues in the definition of the projective measurement 2020-04-21T13:29:36.177

3 Showing measurement of a Hermitian Unitary operator gives final states as eigenvectors 2020-04-28T17:52:12.377

3 Representing a von Neumann measurement as $[\mathcal{I} \otimes P_i] U(\rho_s \otimes \rho_a)U^{-1} [\mathcal{I} \otimes P_i]$, how do we choose $U$? 2020-07-15T14:43:17.730

3 What's the observable when measuring multiple qubits in the computational basis? 2020-08-19T12:21:08.453

3 Can we characterise how correlated the expectation values associated with a pair of observables are? 2020-11-25T16:21:14.223

3 Is a projective measurements over a superposition of eigenstates possible? 2021-01-31T22:14:49.520

2 Projection operators and positive operators 2018-11-20T21:13:14.443

2 Projecting $\lvert ++ \rangle$ on Bell Basis 2019-06-20T08:19:10.600

2 Prove that $P_{M_1}P_{M_2}= P_{M_2}P_{M_1}$ implies $\text{Pr}(\text{span}[M_1, M_2]) = \text{Pr}(M_1)+\text{Pr}(M_2)−\text{Pr}(M_1\cap M_2)$ 2020-04-12T05:17:14.003

2 What's the interpretation of the eigenvalues of qubit's projective operators? 2020-04-21T13:35:35.897

2 Increasing the von Neumann entropy despite the measurement? 2020-05-04T19:47:59.510

1 What does it mean to perform a measurement in correspondence with different projections? 2019-03-10T10:27:05.207

1 How to project a composite system down into a smaller subspace in Python? 2020-12-08T21:34:11.570

0 How to code a projector operator in qiskit? 2020-09-12T23:29:29.683

0 Find the unitary implementing the transformation $|0\rangle\to\frac1{\sqrt2}(|0\rangle+|1\rangle),|1\rangle\to\frac1{\sqrt2}(|0\rangle-|1\rangle)$ 2021-02-11T06:09:27.660