Quantum Signaling to the Past Using P-CTCS

Ghosh, Soumik; Adhikary, Arnab; Paul, Goutam

doi:10.48550/arxiv.1708.03521

Cited by 1 publication

(3 citation statements)

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“…This is to say that P-CTCs suppress all evolutions of nonvacuous states as a result of the particular future evolution of clock states in our model, thereby posing constraints on the initial state. This issue highlights the well-known problem of antichronological and superluminal influence with P-CTCs [9,43,44]. In contrast, the initial data for D-CTCs is never affected by the presence or absence of the CTC in the future.…”

Section: B P-ctcs Constraints On Initial Datamentioning

confidence: 93%

“…Therefore, given the nonlinearity and nonunitarity of D-CTCs and P-CTCs, it unsurprising that they have some very interesting applications. Specifically, both D-CTCs [39] and P-CTCs [40] have uses in distinguishing nonorthogonal quantum states, while D-CTCs [41,42] can clone arbitrary states and P-CTCs can both signal to the past [9,43,44] and delete arbitrary states. Consequences such as these, in addition to the possibility that either theory accurately describes time travel, undeniably motivates further study into D-CTCs and P-CTCs.…”

Section: Comparisonmentioning

confidence: 99%

“…By employing qubit clocks, it is easy to plot the trapped (43) and output (44) probabilities, and such visualisations appear respectively in Figs. 8 and 9.…”

Section: D-ctcs Qubit Visualisationsmentioning

confidence: 99%

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Time-travelling billiard-ball clocks: a quantum model

Bishop,

Costa,

Ralph

2020

Preprint

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We present a novel quantum circuit formulation of the time-travelling billiard ball paradox. We show how the indeterministic histories of the paradox may be emulated via the incorporation of a vacuum state into the circuit's Hilbert space. By employing a quantum clock state, we demonstrate how the multiple self-consistent trajectories of the billiard ball through the chronology-violating region can be distinguished. This technique enables us to rigorously probe the mechanisms of the two foremost quantum theories of time travel: Deutsch's model (D-CTCs) and post-selected teleportation (P-CTCs). The results of this method when applied to our billiard ball paradox circuit prove to be nontrivial. These include observations such as how the suppression of the vacuum subspace forces a particle (clock) to be on the CTC (thereby constraining all trajectories through the circuit to interact with the CTC under both prescriptions), while the inclusion of a vacuum causes the P-CTCs and D-CTCs output states to become a superposition and mixture respectively of the CTC-interacting and CTC-noninteracting histories. We also demonstrate that under certain conditions the P-CTCs results agree with a conjecture made by Friedman et al.

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Section: B P-ctcs Constraints On Initial Datamentioning

confidence: 93%