query: How do I trace out the second qubit to find the reduced density operator?
positive_passages.docid: 122603
positive_passages.text: How does $\mathcal E(\rho)=\mathrm{Tr}_{env}[U(\rho\otimes\rho_{env})U^\dagger]$ turn into $P_0\rho P_0+P_1\rho P_1$?
negative_passages.docid: 83967
negative_passages.text: Why is $|\Psi|^2$ the probability density?
negative_passages.docid: 49090
negative_passages.text: How can I find the $\theta$ and $\phi$ values of a qubit on the Bloch sphere?
negative_passages.docid: 78075
negative_passages.text: Why can I apply $HS^\dagger$ and then measure in the computational basis to measure $Y$?
negative_passages.docid: 90247
negative_passages.text: How to construct matrix of regular and "flipped" 2-qubit CNOT?
negative_passages.docid: 44747
negative_passages.text: Finding the effective Hamiltonian in a certain subspace
negative_passages.docid: 41470
negative_passages.text: Is the density operator a mathematical convenience or a 'fundamental' aspect of quantum mechanics?
negative_passages.docid: 133005
negative_passages.text: I want the QED symbol to be 1 line lower at the end of proof
negative_passages.docid: 147463
negative_passages.text: How would I implement the quantum oracle in Deutsch's algorithm?
negative_passages.docid: 14203
negative_passages.text: Finding the creation/annihilation operators
negative_passages.docid: 69600
negative_passages.text: What is the minimum number of separable pure states needed to decompose arbitrary separable states?
negative_passages.docid: 121389
negative_passages.text: Why is quantum mechancis is not content with symmetric operators, but wants self-adjoint operators?
negative_passages.docid: 138832
negative_passages.text: Expansion coefficients of an arbitrary state in the Hilbert space of one-particle states
negative_passages.docid: 74582
negative_passages.text: How can blackbody radition be explained by quantization?
negative_passages.docid: 96
negative_passages.text: How to interpret a quantum circuit as a matrix?
negative_passages.docid: 159017
negative_passages.text: Bohr-Sommerfeld quantization condition from the WKB approximation
negative_passages.docid: 98771
negative_passages.text: Decomposition of an arbitrary gate using given matrix in Qiskit