Cold atoms store and retrieve weak light pulses carrying orbital angular momentum

What changed

Veissier and colleagues used electromagnetically induced transparency in cold cesium atoms to store and retrieve weak light pulses in two opposite orbital-angular-momentum modes. Mode-selective detection showed that the retrieved light retained the input mode labels; the authors also tested an equal-weight spatial-mode input. In a later related experiment, Nicolas and colleagues measured coherence and performed tomography on stored orbital-mode qubits, reporting fidelities above a benchmark that accounts for weak coherent inputs and the measured retrieval efficiency.

Scientific scope

Veissier and colleagues used electromagnetically induced transparency in cold cesium atoms to store and retrieve weak light pulses in two opposite orbital-angular-momentum modes. Mode-selective detection showed that the retrieved light retained the input mode labels; the authors also tested an equal-weight spatial-mode input. In a later related experiment, Nicolas and colleagues measured coherence and performed tomography on stored orbital-mode qubits, reporting fidelities above a benchmark that accounts for weak coherent inputs and the measured retrieval efficiency. Inputs were weak coherent pulses with mean 0.6 photons per pulse, not certified single-photon Fock states. Reported storage and retrieval efficiency was 16 ± 2% for the two modes and the illustrated delay was 1 microsecond. The two detection channels showed a 9% imbalance for the superposition input, and the authors explicitly state that the coherences and full process fidelity had not been measured. The experiment therefore does not itself establish faithful storage of an arbitrary quantum superposition, entanglement preservation or a higher-dimensional quantum network. Prior bright-beam orbital storage, generic EIT-based storage and the 2001 orbital-entanglement experiment remain separately credited. The 2013 follow-up has its own six-author byline and reports a 1 microsecond storage time, weak coherent pulses of mean 0.6 photons for the tabulated states and approximately 15% retrieval efficiency. It reports 92.5 ± 2% average raw fidelity and 98 ± 1% after background subtraction for those states; its classical benchmark depends on the efficiency and input-photon statistics. This is the later coherence test, not a retroactive claim that the earlier 2012 paper measured coherence. It does not demonstrate storage of entanglement between remote nodes or arbitrary higher-dimensional states. Journal supplementary comparison and raw-data replay remain open. A related 2013 conference abstract gives full names and affiliations; its author order differs from those of the two research papers.

Evidence

The linked original works support the scoped statement and contribution attribution. WRS has not independently replayed experiments or reconstructed a full mathematical proof. Inputs were weak coherent pulses with mean 0.6 photons per pulse, not certified single-photon Fock states. Reported storage and retrieval efficiency was 16 ± 2% for the two modes and the illustrated delay was 1 microsecond. The two detection channels showed a 9% imbalance for the superposition input, and the authors explicitly state that the coherences and full process fidelity had not been measured. The experiment therefore does not itself establish faithful storage of an arbitrary quantum superposition, entanglement preservation or a higher-dimensional quantum network. Prior bright-beam orbital storage, generic EIT-based storage and the 2001 orbital-entanglement experiment remain separately credited. The 2013 follow-up has its own six-author byline and reports a 1 microsecond storage time, weak coherent pulses of mean 0.6 photons for the tabulated states and approximately 15% retrieval efficiency. It reports 92.5 ± 2% average raw fidelity and 98 ± 1% after background subtraction for those states; its classical benchmark depends on the efficiency and input-photon statistics. This is the later coherence test, not a retroactive claim that the earlier 2012 paper measured coherence. It does not demonstrate storage of entanglement between remote nodes or arbitrary higher-dimensional states. Journal supplementary comparison and raw-data replay remain open. A related 2013 conference abstract gives full names and affiliations; its author order differs from those of the two research papers.

Contributors

• The named authors in the research record · SCIENCE: These are the listed authors of the cited contribution sources. Paper authorship does not quantify individual effort. An incomplete list is explicitly marked; same names are not automatically merged.

• A reversible optical memory for twisted photons
• A quantum memory for orbital angular momentum photonic qubits
• A reversible optical memory for twisted photons, DPG Q32.7

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