Quantum discord and steering offer crucial insights into the non-classical nature of hyperon-antihyperon pairs, a massive two-qubit system produced in high energy electron-positron annihilation. This work theoretically investigates the generation and control of these quantum correlations by leveraging longitudinal and transverse polarization of lepton beams. By exploiting the joint spin density matrix of hyperon pairs, the sensitivity of quantum discord and steering to the beam polarization degree are numerically quantified. Our analysis reveals distinct angular regimes where beam polarization can enhance steering and discord. Hierarchy of different quantum correlations are examined under the case of polarized lepton beams by constructing a measure in the spirit of entanglement of formation. It is confirmed that quantum discord remain non-zero even in regions with vanishing entanglement corresponding to separable states, controlled via transversely polarized beams. As an experimentally tunable parameter, beam polarization offers an effective means to manipulate the quantum correlation of hyperon-antihyperon systems, thereby providing a practical route for preparing and probing quantum states in high-energy particle physics.
The Bell nonlocality and entanglement are two kinds of quantum correlations in quantum systems. Due to the recent upgrade in the Beijing Spectrometer III (BESIII) experiment, it is possible to explore the nonlocality and entanglement in hyperon-antihyperon systems produced in electron-positron annihilation with high precision data. We provide a systematic method for studying quantum correlations in spin- 1 / 2 hyperon-antihyperon systems through the measures for the nonlocality and entanglement. We find that with nonvanishing polarizations of the hyperon and its antihyperon, the kinematic region of nonlocality in the hyperon-antihyperon system is more restricted than the τ + τ − system in which polarizations of τ leptons are vanishing. We also present an experimental proposal to probe the nonlocality and entanglement in hyperon-antihyperon systems at BSEIII. Published by the American Physical Society 2024
Hyperon-antihyperon pairs produced from electron-positron annihilations provide a promising platform for exploring quantum-information properties in particle physics. In this work, we analyze quantum steering and quantum discord in hyperon-antihyperon systems produced from e + e − annihilations, based on the X -shaped spin density matrix reconstructed via quantum state tomography. We show that the behaviors of these correlations differ from those observed in elementary particle-antiparticle systems such as top quarks and τ leptons, owing to the polarization effects specific to hyperon decays. From the results, we examine the hierarchy of quantum correlations in hyperon-antihyperon systems, Bell nonlocality ⊂ steering ⊂ entanglement ⊂ discord . We also discuss the role of experimental loopholes and the impact of quantum decoherence in collider-based studies of quantum correlations.
Abstract Hyperon-antihyperon pairs produced in high-energy electron-positron annihilation constitute a naturally spin-entangled system in the high-energy regime. Recently, a probabilistic amplification of entanglement, termed autodistillation, has been found in the daughter baryon-antibaryon pairs from hyperon decay and is constrained by an upper boundary. This work demonstrates that the quantum entanglement in this process may be accompanied by a decrease, constrained by a lower boundary, but it will not be completely lost. Thus, the entanglement of these systems undergoes redistribution within the phase space during the sequential decays of hyperons, highlighting the important role of hyperon polarization. By using the explicit spin density matrix of baryon pairs, it is also found that the quantumness of the system, characterized by quantum discord, always has the possibility to increase during decay processes, even when entanglement evaluated by concurrence and negativity does not increase.
We present a quantum tomography study of fermion pair production at future
e+e− colliders, emphasizing how longitudinal beam polarization controls the two-qubit spin density matrix. We study the processes
e+e−→ttˉ, e+e−→μ+μ− and Bhabha scattering
e+e−→e+e−, representing the mass threshold behavior, the
Z pole resonance and the
s/t-channel interplay. We choose to focus on three key concepts: quantum entanglement via the concurrence
C, Bell nonlocality via the optimal Clauser Horne Shimony Holt (CHSH) parameter
B, and non-stabilizerness (``magic'') via the second stabilizer Rényi entropy
M2. For the
s-channel-dominated channels, longitudinal polarization mainly reshapes single-spin polarizations while leaving the spin-correlation matrix largely unchanged, rendering
C and
B comparatively robust, but inducing a pronounced variation of
M2. In contrast, in Bhabha scattering, polarization modifies the relative contributions of the
s-channel and
t-channel and can strongly affect all three observables. The observability of entanglement, Bell nonlocality, and magic exceeds the
5σ level when both statistical and systematic uncertainties are included, establishing the fermion pair systems as ideal laboratories for quantum-information studies in high energy leptonic collisions. With optimized beam polarization, future
e+e− colliders will provide a unique opportunity to experimentally explore and influence quantum resources in particle interactions.
A bstract A photon linear collider, the two-photon collision mode of an e + e − linear collider, uses high-energy laser photons backscattered off the incoming electrons and positrons. The colliding-photon polarization is fully controllable through the polarizations of the initial electron and positron beams and laser photons. We investigate the impact of colliding-photon polarization on the observability of quantum entanglement in top-quark pair production at a photon linear collider. Constructing the spin density matrix of the
tt two-qubit system from the helicity amplitudes, we demonstrate that a photon linear collider is an ideal machine to probe quantum entanglement and Bell nonlocality across the broad phase space of the process.