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arXiv:1912.04798 · Physical review. D/Physical review. D.

Can future observation of the living partner post-tag the past decayed state in entangled neutral K mesons?

J. Bernabéu, ANTONIO DI DOMENICO

Published Jun 3, 2022• 10 citations

Abstract

Entangled neutral $K$ mesons allow for the study of their correlated dynamics at interference and decoherence times not accessible in any other system. We find novel quantum phenomena associated to a correlation in time between the two partners: The past state of the first decayed kaon, when it was entangled before its decay, is post-tagged by the result and the time of the future observation of the second decay channel. This surprising ``from future to past'' effect is fully observable and leads to the unique experimental tag of the ${K}_{S}$ state, an unsolved problem since the discovery of $CP$ violation.

DOI: 10.1103/physrevd.105.116004

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Entangled neutral

K

mesons allow for the study of their correlated dynamics at interference and decoherence times not accessible in any other system. We find novel quantum phenomena associated to a correlation in time between the two partners: The past state of the first decayed kaon, when it was entangled before its decay, is post-tagged by the result and the time of the future observation of the second decay channel. This surprising ``from future to past'' effect is fully observable and leads to the unique experimental tag of the

{K}_{S}

state, an unsolved problem since the discovery of

CP

violation.

Entangled neutral K-mesons allow the study of their correlated dynamics at interference and decoherence times not accessible in any other system. We find novel quantum phenomena associated to a correlation-in-time between the two partners: the state of the first decayed Kaon, when it was entangled before its decay, is influenced by the result and the time of the future observation of the second decay channel. This surprising from future to past effect is fully observable and leads to the unique experimental tag of the KS-state, an unsolved problem since the discovery of CP violation.

Abstract Novel quantum phenomena have been recently discussed [1] in association to a peculiar time correlation between entangled neutral kaons produced at a ϕ-factory: the past state of the first decayed kaon, when it was still entangled before its decay, is post-tagged by the result and the time of the future observation on the other kan decay. This surprising “from future to past” effect is fully observable and leads to the unique experimental tag of the KS state, an unsolved problem since the discovery of CP violation. The first preliminary results obtained on the analysis of data collected by the KLOE experiment at the DAΦNE collider, and showing experimental evidence of this new effect are presented.

The Einstein-Podolsky-Rosen (EPR) entanglement of a neutral K-meson (kaon) pair enjoys the peculiar quantum behaviour of mixing, charge-parity

{\cal CP}

violation (

{\cal C}

- charge conjugation,

{\cal P}

- parity) and two non-orthogonal eigenstates of definite time evolution

K_L

and

K_S

with very different lifetimes. The dynamics of this strange entanglement, experimentally accessible at the

\phi

-factory, makes possible the search for novel phenomena not accessible in any other system, i.e. at interference times and at decoherence times of the single partners after their disentanglement, in order to unveil the nature of the correlation between the two neutral kaons. Until now, the studies have been concentrated on the single kaon intensity distribution between the two decay times

t_1

and

t_2

with

\Delta t = t_2 - t_1 > 0

. Here we show that the entire two single time distributions, before each decay, are physical in both senses: past to future, leading to the state of the living partner at time

t_2

from the observation of the first decay channel at

t_1

, and future to past, leading to the past state of the decayed kaon at time

t_1

from the observation of the second decay channel at

t_2

. Our results thus demonstrate an affirmative answer to the title: it does, the past decayed state depends on the result of the future measurement for the living partner. This novel effect is truly observable through the first decay time distributions. Besides the implications for quantum physics for all

\Delta t

, at large decoherence times the resulting first decayed state is always

K_S

, providing a genuine tag of this kaon state in the decoherence region, and a unique and important experimental tool to prepare a pure

K_S

beam.

Novel quantum phenomena have been recently discussed in association to a peculiar time correlation between entangled neutral kaons produced at a

\phi

-factory: the past state of the first decayed kaon, when it was still entangled before its decay, is post-tagged by the result and the time of the future observation on the other kaon decay. This surprising ``from future to past'' effect is fully observable. Preliminary results obtained on the analysis of data collected by the KLOE experiment at the DA

\Phi

NE collider are presented, showing experimental evidence of this new effect.

In a

ϕ

factory, neutral kaons are produced in Einstein-Podolsky-Rosen (EPR) states, furthermore, a

K_S

is tagged if its entangled partner is detected as

K_L

, and vice versa. Here we point out that upon its detection as

\phi

, one of the EPR-entangled particles is projected into one of the orthogonal basis states, consequently the other particle should be projected to the state orthogonal to

K_L

, denoted as

K_{\perp L}

, rather than

K_S

, because

K_S

is not orthogonal to

K_L

. Therefore the semileptonic charge asymmetry of what was previously regarded as

K_S

is really that of

K_{\perp L}

. Based on this re-tagging, we modify the experimentally determined values of several parameters, including the one describing the violation of

ΔS = ΔQ

rule, the one describing CPT violation for

ΔS = ΔQ

transitions, and the time-like CPT- and Lorentz-violating coefficient for the two valence quarks in a kaon.

In the system of a pair of quantum-entangled neutral kaons from meson decays, when one kaon collapses into the [Formula: see text] state, the other will collapse instantaneously into the [Formula: see text] state, due to entanglement and nonlocality. However, if the alternative hypothesis is correct and there is a time window during which one kaon is unaware that the other has decayed, some quantum mechanically prohibited [Formula: see text] decays may occur. We calculate the branching ratios of [Formula: see text] in vector meson decays under locality hypothesis and compare them with experimental results. We show that the branching ratio of [Formula: see text] under locality assumption is already excluded by the BESIII experimental upper limit. Additional experimental results are proposed to perform this test in the future.