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For questions about mathematical problems arising from quantum mechanics, a branch of physics describing the behaviour of nature at very small scales, at the level of atoms and subatomic particles.

3 votes
Accepted

Interpretation of a parameter in forming a pseudodifferential operator

Let me answer to your second query and make $h=1$. You have $$ Op_1(a(x) \xi)= a(x) D_x,\quad \text{with $D_x=-i\partial_x$}, $$ $$ Op_0(a(x) \xi)= D_x a(x), $$ $$ Op_{1/2}(a(x) \xi)= \frac 12D_x a(x) …
Bazin's user avatar
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7 votes
Accepted

Is there an equivalent of Heisenberg's uncertainty principle in the decision sciences ?

Let me answer in terms of operator theory. The uncertainty principle can be interpreted as some particular inequality (as you say) such as $$ \frac{\hbar}{2}\Vert{u}\Vert^2\le \Vert{D_xu}\Vert\Vert{xu …
Bazin's user avatar
  • 16.2k
1 vote

Observable nearly commuting with a "complete" set of commuting observables

Well, you have $$ [\frac{1}{idx},x]=1/i $$ although $\frac{1}{idx}$ is far from the Identity.
Bazin's user avatar
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2 votes
Accepted

Massive dirac operator symmetric spectrum

With $z=x+iy$, we use the Fourier transformation in $(x,y)$ to see that $H$ is unitarily equivalent to $$ \frac12\begin{pmatrix}2m&\xi-i\eta\\ \xi+i\eta&-2m\end{pmatrix}, \text{whose eigenvalues are } …
Bazin's user avatar
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8 votes
1 answer
455 views

On commutator of bounded operators

Let $\mathbb H$ be a Hilbert space and let $\mathcal B(\mathbb H)$ be the bounded operators on $\mathbb H$. Let $J,K\in \mathcal B(\mathbb H)$ such that $ J=J^*, K=-K^*. $ Then the commutator $[J,K]$ …
Bazin's user avatar
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1 vote
Accepted

Witten index non-trivial in the context of Quantum Mechanics?

Consider the most classical example, $D=\frac{d}{dx}-x$, which is the creation operator. Note that $D$ is injective since, with $L^2$ norms and dot-products and say $u$ in the Schwartz class, $$ \Vert …
Bazin's user avatar
  • 16.2k
0 votes

Is there a 'certainty' principle?

With $D_x=\frac{d}{i dx}$, the Heisenberg uncertainty principle in its most classical form can be deduced from the equality $$ 2\Re \langle \hbar D_x u, ix u \rangle_{L^2(\mathbb R)}= \langle \bigl[\h …
Bazin's user avatar
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4 votes

When is this operator positive semi-definite?

Too long for an additional comment. I guess that you can keep the assumption $\hat P, \hat Q$ Hermitian and require $$ [\hat P, \hat Q]=1/(2πi), $$ as it is the case with the prototypical example $ \h …
Bazin's user avatar
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