Description
Quantum state tomography provides a complete characterisation of quantum systems through measurements performed in multiple complementary bases [1], enabling the reconstruction of the system's density matrix and the quantification of coherence and entanglement. Here, we report the implementation of quantum state tomography for momentum-entangled atom pairs generated in a double-halo source and analysed using a dual-resonant matter-wave Rarity–Tapster interferometer [2,3]. By performing correlation measurements in multiple independently controlled momentum bases, we reconstruct the complete two-particle density matrix, providing a full characterisation of the entangled quantum state.
The reconstructed density matrix enables quantitative evaluation of the coherence, purity, entropy, and entanglement of the momentum-entangled atom pairs [4], providing a more complete description of the system than measurements of individual observables or Bell correlations alone [5]. This approach provides direct access to the quantum correlations encoded in the atomic momentum modes and establishes a solid framework for benchmarking the fidelity of entangled matter-wave sources.
Complete characterisation of the quantum state is essential for translating entangled matter-wave systems into practical quantum technologies. Quantum state tomography certifies the generated resource for applications in quantum-enhanced metrology and quantum information and communication [6], while the double halo geometry and dual-resonant interferometer provide a versatile platform for studying quantum correlations and developing technologies with massive particles.
References
[1] G. Mauro D’Ariano et al., Quantum Tomography, in Advances in Imaging and Electron Physics, edited by P. W. Hawkes, Vol. 128 (Elsevier, 2003), pp. 205–308.
[2] C. Leprince, Phys. Rev. A 111, (2025).
[3] K. F. Thomas et al., Eur. Phys. J. D 76, 244 (2022).
[4] J. B. Altepeter et al., Photonic State Tomography, in Advances In Atomic, Molecular, and Optical Physics, Vol. 52 (Elsevier, 2005), pp. 105–159.
[5] Y. S. Athreya et al., Nat. Commun. 17, 2357 (2026).
[6] S. Pironio et al., Nature 464, 1021 (2010).
| I am the presenting author | Yes |
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