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| bio | website | |
|---|---|---|
| location | Russia | |
| age | ||
| visits | member for | 2 years |
| seen | May 5 '12 at 20:03 | |
| stats | profile views | 235 |
Scientist
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May 4 |
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Information conservation during quantum measurement in $\psi$-epistemic interpretations May be interesting: mathoverflow.net/questions/95537/… |
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Apr 4 |
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Negative probabilities in quantum physics Feynman wrote in this essay: "Trying to think of negative probabilities gave me a cultural shock at first, but when I finally got easy with the concept I wrote myself a note so I wouldn't forget my thoughts." |
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Mar 26 |
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Multiqubit state tomography by performing measurement in the same basis @Piotr Migdal: Using other words I am simply showing that the set of that nonorthogonal measurements is not "informationally complete". |
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Mar 26 |
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Multiqubit state tomography by performing measurement in the same basis Even measurement in single basis produces $2^n-1$ parameters. My preliminary estimation give equation $\sum_k C^n_k C^{k+2}_k$, but seems Chris' curve corresponds a bit different values. |
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Mar 25 |
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Multiqubit state tomography by performing measurement in the same basis Indeed, I see - $\rho_1 = (1 + \sigma_z \otimes \sigma_x)/4$, $\rho_2 = (1 + \sigma_x \otimes \sigma_z)/4$. |
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Mar 25 |
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Multiqubit state tomography by performing measurement in the same basis @Peter Shor: I already wrote, I do not require that - we may distinuish the swap of all components due to assymetry between $\sigma_0 \otimes \sigma_k$ and $\sigma_k \otimes \sigma_0$. |
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Mar 25 |
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Multiqubit state tomography by performing measurement in the same basis @Peter Shor: they are equal only for $k,j \neq 0$ but it is not so for terms with $\sigma_0 =1$ (so my note about "a swap operator" in earlier answer was misleading). |
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Mar 9 |
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Analyticity and Causality in Relativity I doubt an answer may be short. From experience of discussion about that problem (also confirmed by answers and comments here) I learn, that even statement of the problem is not very simple. One my colleague even had idea to use it as PhD theme ... |
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Feb 20 |
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Constructing a Hamiltonian (as a polynomial of $q_i$ and $p_i$) from its spectrum I think, the Newton interpolation formula may be used instead of Gaussian elimination in this case |
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Jan 21 |
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Time reversal symmetry and T^2 = -1 I could better understand a question $Pin(3,1)$ vs $Pin(1,3)$. How we could answer what we are using in Euclidean case? Even in Lorentzian case we sometimes have to talk about experimental data (e.g. discovery of antiparticles, search for Majorana neutrino, etc.) to clarify such questions. |
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Dec 3 |
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Charged black holes in equilibrium It is quite common to claim that even single black hole does not result a stationary spacetime lightandmatter.com/html_books/genrel/ch07/ch07.html |
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Nov 29 |
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Is this a simple Lie algebra? In such a case OP could write $[i\sigma_a,i\sigma_b]=\cdots$. It is not a convention, it is rather a convenient trick to work with Lie algebra of unitary group, because the algebra is anti-Hermitian matrices. If to use the convention without warning we could not distinguish $sl(2,C)$ and $su(2)$ |
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Nov 24 |
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Hilbert-Schmidt basis for many qubits - reference Maybe the discrete Wigner function is a bit other story, because they need to use trace on $GF(2^n)$ and exchange components in Hilbert-Schmidt scalar product. |
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Nov 24 |
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Is this a simple Lie algebra? It is rather $so(4,{\mathbb C}) \approx sl(2,{\mathbb C}) \oplus sl(2,{\mathbb C})$, because OP defines it as a complex algebra. |
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Nov 24 |
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Is this a simple Lie algebra? @Luboš Motl: any Pauli matrix meets two last equations and after all ${\rm diag}(+1,-1)$ is also Pauli matrix $\sigma_z$. |
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Nov 23 |
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Hilbert-Schmidt basis for many qubits - reference I guess, but I never heard about simple expressions for constrains |
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Nov 23 |
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Hilbert-Schmidt basis for many qubits - reference I supposed the decomposition itself is rather standard consequence of axioms of quantum mechanics and linear algebra, e.g. section 5.3 in my e-print arxiv.org/abs/quant-ph/0104126v1 |
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Nov 22 |
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Hilbert-Schmidt basis for many qubits - reference So the term due to Hilbert-Schmidt inner product for matrices? |
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Nov 22 |
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Hilbert-Schmidt basis for many qubits - reference It is simply decomposition of $4^n$ dimensional “vector” with an orthogonal basis. Vector space is space of $2^n \times 2^n$ Hermitian matrices with respect to norm $(A,B) =Tr(AB) = Tr(AB^*)$. But I doubt, it could be called Hilbert-Schmidt decomposition because it is defined for any $n$ and for $n=2$ produces up to 16 terms instead of 4. |
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Nov 22 |
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What proof techniques have failed for solving the SIC-POVM problem and what new insights have been gleaned from them? Just mentioned related question on MO mathoverflow.net/questions/2897/… |
