arXiv subjects

Patrick Blackstone

Publications and source records attributed to Patrick Blackstone.

2 recordsLinked to original sources

arXiv2021

Quantum Entangled-Probe Scattering Theory

We develop an entangled-probe scattering theory, including quantum detection, that extends the scope of standard scattering approaches. We argue that these probes may be revolutionary in studying entangled matter such as unconventional phases of strongly correlated systems. Our presentation focuses on a neutron beam probe that is mode-entangled in spin and path as is experimentally realized in [1], although similar ideas also apply to photon probes. We generalize the traditional van Hove theory [2] whereby the response is written as a properly-crafted combination of two-point correlation functions. Tuning the probe's entanglement length allows us to interrogate spatial scales of interest by analyzing interference patterns in the differential cross-section. Remarkably, for a spin dimer target we find that the typical Young-like interference pattern observed if the target state is un-entangled gets quantum erased when that state becomes maximally entangled.

quant-ph↗

arXiv2020

$τ\to μμμ$ at a rate of one out of $10^{14}$ tau decays?

We present in a full analytic form the partial widths for the lepton flavour violating decays $μ^\pm \to e^\pm e^+ e^-$ and $τ^\pm \to \ell^\pm \ell'^{+} \ell'^{-}$, with $\ell,\ell'=μ,e$, mediated by neutrino oscillations in the one-loop diagrams. Compared to the first result by Petcov in [1], obtained in the zero momentum limit $\mathcal{P}\ll m_ν \ll M_W$, we retain full dependence on $\mathcal{P}$, the momenta and masses of external particles, and we determine the branching ratios in the physical limit $m_ν\ll \mathcal{P} \ll M_W$. We show that the claim presented in [2] that the $τ\to \ell \ell' \ell'$ branching ratios could be as large as $10^{-14}$, as a consequence of keeping the $\mathcal{P}$ dependence, is flawed. We find rates of order $10^{-55}$, even smaller than those obtained in the zero momentum limit, as the latter prediction contains an unphysical logarithmic enhancement.

hep-ph↗