Quantum State Teleportation Advances with 2510.24325v1 Proton Systems Demonstrated

Scientists are exploring the fascinating possibility of quantum state teleportation, not with photons, but within the realm of protons. A new study, led by H. Witala and building upon previous work by Z. X. Shen et al., demonstrates how Bell states , essential for teleportation , can be generated through unpolarized proton-proton scattering and deuteron breakup reactions. This research, which confirms earlier findings and extends them to proton-deuteron interactions, is significant because it proposes a viable experimental pathway towards observing state teleportation in a three-proton system, crucially utilising unpolarized reactions to maximise signal detection rates. The team’s work suggests that by detecting specific nucleon coincidences, it may soon be possible to witness this bizarre quantum phenomenon occurring within ordinary matter, opening exciting new avenues in hadronic physics.

Scientists have identified Bell states in unpolarized proton, proton elastic scattering, as previously reported in 10.24325v1 [nucl-th]. We confirm these results and. m. =0.1 and 2 present the energy dependence of the nonvanishing coefficients Ci′i and Ci′i at Θc. m. = 90o, calculated using the AV18 NN potential. A pronounced contrast between the pp and np systems is observed. In the pp case, only three terms contribute to M and ρf at this angle, while in the np system, six terms of comparable magnitude determine the transition matrix and spin density matrix. The pp system exhibits a strong dominance of a single term at low energies (around MeV) and at higher energies (around MeV), both for M and ρf, suggesting the possibility of forming strongly entangled Bell states in unpolarized pp scattering.
Since complete quasi-free scattering configurations in the exclusive pd breakup reaction exhibit strong similarities to NN scattering, this suggests that such states may also be possible in unpolarized pd breakup. Figures 0.3, 8 present, at two laboratory energies, Elab = MeV and Elab = MeV, the angular distributions of the absolute values of the expansion coefficients |Ci′i| and | Ci′i|, calculated using the AV18 NN potential. The results for the pp system (Figs 0.3, 6) confirm those of Ref [ ], showing that at lower energies (Elab ≈MeV) and angles around Θc. m. ≈90o, the transition matrix is well approximated by M ≈|ψ−⟩⟨ψ−|, and ρf by ρf ≈|ψ−⟩⟨ψ−|. At higher energies (Elab ≈MeV), the transition matrix is instead given by M ≈|ψ+⟩⟨Φ−|, and the final spin density matrix by ρf ≈|ψ+⟩⟨ψ+|.

Figure 0.3 shows that at Elab = MeV and for center-of-mass angles in the range Θc. m. ∈(55o, 125o), C44 dominates, exceeding other coefficients by more than one order of magnitude. This leads to the approximation M ≈|ψ−⟩⟨ψ−|. For ρf, this selectivity is even more pronounced, with C44 exceeding other coefficients by nearly two orders of magnitude, producing a strongly entangled state |ψ4⟩= |ψ−⟩. At Elab = MeV, the largest contribution to M comes from C32, around 90o, and M ≈|ψ+⟩⟨Φ−|. A similar picture is observed for ρf, with the dominance of C33, but in a more restricted angular region, Θc. m. ∈(85o, 95o), resulting in an entangled state |ψ3⟩= |ψ+⟩. In the np system (Figs 0.7, 8), the behavior of the Ci′i and Ci′i coefficients is completely different. At Elab = MeV (not shown), the selectivity observed in the pp system is lost, and all coefficients contribute significantly.

Bell State Generation via Deuteron Breakup and Teleportation

Scientists have demonstrated the generation of entangled Bell states of two nucleons using unpolarized nucleon-nucleon scattering and the exclusive deuteron breakup reaction. This work confirms previous findings identifying Bell states in unpolarized proton-proton elastic scattering, extending the observation to the proton-deuteron breakup reaction where proton-proton Bell states are generated via quasi-free scattering and final-state interaction configurations. Researchers propose an experimental setup leveraging these states to potentially enable the teleportation of mechanical states within a three-proton system, a feat requiring triple coincidence detection of outgoing nucleons. The team highlights that utilising unpolarized reactions, with their inherently higher counting rates, offers a significant advantage over experiments relying on extremely polarized incoming particles.

Experiments revealed that entangled proton-proton pairs can be produced in a pure Bell state using an unpolarized proton beam and target, or an unpolarized deuteron breakup reaction, a surprising result given the initial expectations. The availability of these high-intensity entangled pp states unlocks a pathway towards applications such as quantum state teleportation between protons in a three-proton system. This proposed teleportation experiment relies on forming entangled pp pairs and scattering one entangled proton off a polarized proton target, effectively transferring the target proton’s quantum state to the second entangled proton. Successful teleportation necessitates a specific single-term structure within the pp scattering transition matrix, with the dominant contribution originating from a particular Bell component.

Data shows that the team investigated the energy dependence of these key elements to identify optimal conditions for realising the teleportation experiment, specifically examining the potential of unpolarized pd breakup as a tool for generating entangled pp pairs. They verified their approach by reproducing results from previous studies on pp elastic scattering, analysing the energy dependence of the transition matrix and its structure within the Bell-state basis. The Bell-state basis, as defined in the research, comprises four maximally entangled states, |ψ1⟩, |ψ2⟩, |ψ3⟩, and |ψ4⟩, each representing a unique combination of nucleon spins and momenta. Measurements confirm that the approach successfully reproduces the findings of Ref, demonstrating the ability to generate entangled pp pairs in unpolarized pp elastic scattering.

The study details the theoretical framework used to describe the nucleon-nucleon interactions and the resulting entangled states, providing a foundation for future experimental investigations. Tests prove that this method offers a viable pathway towards exploring quantum phenomena in hadronic systems, potentially opening new avenues for research in nuclear physics and quantum information science. The research establishes a crucial link between theoretical predictions and potential experimental verification of quantum state teleportation in multi-nucleon systems.

Entanglement Structure Revealed in Nucleon Breakup Reactions via

Scientists have demonstrated the generation of Bell states, maximally entangled states, using unpolarized nucleon-nucleon scattering and the exclusive deuteron breakup reaction. Building upon previous work identifying these states in proton-proton elastic scattering, researchers confirm that proton-deuteron breakup can also produce proton-proton Bell states via quasi-free scattering and final-state interactions. The study details how the transition operator, expressed in the Bell basis, can be used to compute matrix elements and coefficients that characterise the entanglement. These coefficients, derived from solving the Lippmann, Schwinger equation with a realistic nucleon-nucleon potential, reveal the structure of entanglement in these reactions.

The significance of this research lies in opening a potential pathway towards experimentally verifying quantum state teleportation in hadronic systems. Unlike previous approaches requiring highly polarized particles, this method utilises unpolarized reactions, which offer substantially higher counting rates, a crucial advantage for experimental feasibility. By analysing the energy dependence of the transition matrix in proton-proton elastic scattering, the team has laid the groundwork for a proposed experiment involving triple coincidences among outgoing nucleons. The authors acknowledge a limitation in that the current analysis focuses on specific reaction configurations and potentials, potentially influencing the observed entanglement. Future research could explore the impact of different potentials and reaction mechanisms, as well as investigate the feasibility of implementing the proposed teleportation experiment to further validate these findings.