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Interaction-free measurements by quantum Zeno stabilization of ultracold atoms.

Peise J, Lücke B, Pezzé L, Deuretzbacher F, Ertmer W, Arlt J, Smerzi A, Santos L, Klempt C - Nat Commun (2015)

Bottom Line: Quantum mechanics predicts that our physical reality is influenced by events that can potentially happen but factually do not occur.Contrary to existing proposals, our IFM does not require single-particle sources and is only weakly affected by losses and decoherence.We demonstrate confidence levels of 90%, well beyond previous optical experiments.

View Article: PubMed Central - PubMed

Affiliation: Institut für Quantenoptik, Leibniz Universität Hannover, Welfengarten 1, D-30167 Hannover, Germany.

ABSTRACT
Quantum mechanics predicts that our physical reality is influenced by events that can potentially happen but factually do not occur. Interaction-free measurements (IFMs) exploit this counterintuitive influence to detect the presence of an object without requiring any interaction with it. Here we propose and realize an IFM concept based on an unstable many-particle system. In our experiments, we employ an ultracold gas in an unstable spin configuration, which can undergo a rapid decay. The object-realized by a laser beam-prevents this decay because of the indirect quantum Zeno effect and thus, its presence can be detected without interacting with a single atom. Contrary to existing proposals, our IFM does not require single-particle sources and is only weakly affected by losses and decoherence. We demonstrate confidence levels of 90%, well beyond previous optical experiments.

No MeSH data available.


Related in: MedlinePlus

Realization of the atomic homodyning.After an evolution in the presence or absence of an absorbing object in the (1, −1) state (1), we transfer the remaining atoms in the (1, 0) state to (2, 0) with a microwave pulse (2). These atoms act as a strong coherent state for the displacement of the state in (1, −1) by a short microwave pulse (3).
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f5: Realization of the atomic homodyning.After an evolution in the presence or absence of an absorbing object in the (1, −1) state (1), we transfer the remaining atoms in the (1, 0) state to (2, 0) with a microwave pulse (2). These atoms act as a strong coherent state for the displacement of the state in (1, −1) by a short microwave pulse (3).

Mentions: For the implementation of the unbalanced homodyne detection in our experiments, the remaining condensate in (1, 0) can be used as the strong coherent state. As all particle numbers are measured in the end, the state is indeed closer to a Fock state. We have checked, however, that at these large particle numbers, the homodying results for Fock and coherent state are equivalent. For the realization of the unbalanced beam splitter, we first transfer these atoms to the (2, 0) level and then apply a short microwave pulse to couple the coherent state to the state created in the (1, +1) level (see Fig. 5). If no atoms are present in the (1, +1) level, this pulse transfers about cos2θ=8% of the condensate, where θ=ωt with the microwave Rabi frequency ω and the pulse duration t.


Interaction-free measurements by quantum Zeno stabilization of ultracold atoms.

Peise J, Lücke B, Pezzé L, Deuretzbacher F, Ertmer W, Arlt J, Smerzi A, Santos L, Klempt C - Nat Commun (2015)

Realization of the atomic homodyning.After an evolution in the presence or absence of an absorbing object in the (1, −1) state (1), we transfer the remaining atoms in the (1, 0) state to (2, 0) with a microwave pulse (2). These atoms act as a strong coherent state for the displacement of the state in (1, −1) by a short microwave pulse (3).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4403339&req=5

f5: Realization of the atomic homodyning.After an evolution in the presence or absence of an absorbing object in the (1, −1) state (1), we transfer the remaining atoms in the (1, 0) state to (2, 0) with a microwave pulse (2). These atoms act as a strong coherent state for the displacement of the state in (1, −1) by a short microwave pulse (3).
Mentions: For the implementation of the unbalanced homodyne detection in our experiments, the remaining condensate in (1, 0) can be used as the strong coherent state. As all particle numbers are measured in the end, the state is indeed closer to a Fock state. We have checked, however, that at these large particle numbers, the homodying results for Fock and coherent state are equivalent. For the realization of the unbalanced beam splitter, we first transfer these atoms to the (2, 0) level and then apply a short microwave pulse to couple the coherent state to the state created in the (1, +1) level (see Fig. 5). If no atoms are present in the (1, +1) level, this pulse transfers about cos2θ=8% of the condensate, where θ=ωt with the microwave Rabi frequency ω and the pulse duration t.

Bottom Line: Quantum mechanics predicts that our physical reality is influenced by events that can potentially happen but factually do not occur.Contrary to existing proposals, our IFM does not require single-particle sources and is only weakly affected by losses and decoherence.We demonstrate confidence levels of 90%, well beyond previous optical experiments.

View Article: PubMed Central - PubMed

Affiliation: Institut für Quantenoptik, Leibniz Universität Hannover, Welfengarten 1, D-30167 Hannover, Germany.

ABSTRACT
Quantum mechanics predicts that our physical reality is influenced by events that can potentially happen but factually do not occur. Interaction-free measurements (IFMs) exploit this counterintuitive influence to detect the presence of an object without requiring any interaction with it. Here we propose and realize an IFM concept based on an unstable many-particle system. In our experiments, we employ an ultracold gas in an unstable spin configuration, which can undergo a rapid decay. The object-realized by a laser beam-prevents this decay because of the indirect quantum Zeno effect and thus, its presence can be detected without interacting with a single atom. Contrary to existing proposals, our IFM does not require single-particle sources and is only weakly affected by losses and decoherence. We demonstrate confidence levels of 90%, well beyond previous optical experiments.

No MeSH data available.


Related in: MedlinePlus