All Questions
Tagged with cpt-symmetry quantum-mechanics
14
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Confused about square of time-reversal operator $T$
I am reading An Introduction to Quantum Field Theory by Peskin & Schroeder, and I am confused about what is the square $T^2$ of time reversal operator $T$.
My guess is that for $P^2$, $C^2$ and $T^...
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Non-Hermitian PT-symmetric Interacting Hamiltonian with Real Spectra
The following hamiltonian is $\mathcal{PT}$-symmetric $$\mathcal{H} = -J \sum_{j = 1}^{2N} [ 1 + (-1)^j \delta ] [ c^{\dagger}_{j} c_{j+1} + h.c. ] + \imath \gamma \sum_{j = 1}^{2N} (-1)^j c^{\dagger}...
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Is really hermiticity necessary to be a physical observable? What about larger class of operators like PT invariant operators or pseudo hermitian one?
It's really necessary for an observable represented by an operator acting in a Hilbert space to be hermitian?
It's known that not only hermitian operators have real eigenvalues and that also normal ...
- 310
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Complex conjugation in time-reversal $T$ symmetry v.s. in charge conjugation $C$ symmetry
How is the complex conjugation $K$ of time-reversal symmetry $T$ differed by the complex conjugation of charge conjugation $C$? How are they differed from each other?
For instance, take the Dirac ...
- 593
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Zee's book on QFT on the spin-1/2 state has $T^2=-1$, why not $T^2=+1$
In Zee's book on QFT, p.103, he showed that the spin-1/2 state has $T^2=-1$ by finding that the $T = UK$ has a matrix $U\propto \sigma_2$ and a complex conjugation $K$.
However, how do we know that we ...
- 593
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Critique on various ways to think about time reversal transformation on Schrodinger equation?
Please define how time-reversal symmetry act on Schrodinger equation $i \frac{\partial}{\partial t} |\Psi{}(t) \rangle = H(t) |\Psi{}(t) \rangle.$ (for general form: which can be relativistic such as ...
- 4,336
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Does the time reversal flip the differential measure $dt$?
Does the time reversal flip the differential measure $dt$ or integral measure $dt$?
Does the time reversal flip the differential measure $dt$ or $\Delta t$?
Suppose we look at the derivative on a ...
- 4,336
3
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Difference between non-Hermitian and PT-symmetric systems [closed]
Can anyone explain me the difference between non-Hermitian and PT-symmetric systems (in terms of the Hamiltonian)? Are they two mutually exclusive things?
user274797
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What is CPT, really?
The naive statement for the "CPT theorem" one usually finds in the literature is "relativistic theories should be CPT invariant". It is clear that this statement is not true as written, e.g. ...
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Are all processes time/CPT-reversible, e.g. measurement, stimulated emission, state preparation, Big Bang?
"The CPT theorem says that CPT symmetry holds for all physical phenomena, or more precisely, that any Lorentz invariant local quantum field theory with a Hermitian Hamiltonian must have CPT symmetry." ...
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Clarifying PT symmetry
I understand that if a Hamiltonian remains invariant under the following transformations then it is PT invariant,
\begin{eqnarray}
\mathrm{Parity \; reversal:} \; \; \hat{p} \to -\hat{p} \; \; \...
- 131
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How to understand $T^2=(-1)^{N_f}$ in terms of operator matrices on Hilbert space
For a time reversal symmetry operator $\hat{T}$, we have
$$\hat{T}^2=(-1)^{N_f}$$
for a fermionic (electronic) system. How do we understand $\hat{T}^2=(-1)^{N_f}$ in terms of operator matrices on the ...
- 4,336
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Wave function of particle and antiparticle
The wave functions of particle and antiparticle are related by complex conjugation and wavefunction $Ψ$ must be complex for particle such as $n$, $p$. Is there way to prove this mathematically? Can we ...
- 153
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Neutron electric dipole moment and $T$ symmetry violation
Our textbook (and other sources I have found) says that non-zero electric dipole moment of neutron would violate $T$ symmetry. They prove this statement by first assuming $\boldsymbol{D}=\beta\...
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