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Interaction-induced decay of a heteronuclear two-atom system.

Xu P, Yang J, Liu M, He X, Zeng Y, Wang K, Wang J, Papoular DJ, Shlyapnikov GV, Zhan M - Nat Commun (2015)

Bottom Line: One of the key quantities is the inelastic relaxation (decay) time when one of the atoms or both are in a higher hyperfine state.This experimental method allows us to single out a particular relaxation process thus provides an extremely clean platform for collisional physics studies.Our results have also implications for engineering of quantum states via controlled collisions and creation of two-qubit quantum gates.

View Article: PubMed Central - PubMed

Affiliation: 1] State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, and Wuhan National Laboratory for Optoelectronics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, China [2] Center for Cold Atom Physics, Chinese Academy of Sciences, Wuhan 430071, China.

ABSTRACT
Two-atom systems in small traps are of fundamental interest for understanding the role of interactions in degenerate cold gases and for the creation of quantum gates in quantum information processing with single-atom traps. One of the key quantities is the inelastic relaxation (decay) time when one of the atoms or both are in a higher hyperfine state. Here we measure this quantity in a heteronuclear system of (87)Rb and (85)Rb in a micro optical trap and demonstrate experimentally and theoretically the presence of both fast and slow relaxation processes, depending on the choice of the initial hyperfine states. This experimental method allows us to single out a particular relaxation process thus provides an extremely clean platform for collisional physics studies. Our results have also implications for engineering of quantum states via controlled collisions and creation of two-qubit quantum gates.

No MeSH data available.


Related in: MedlinePlus

Experimental data for the decay rates.(a) Energy levels of hyperfine states of 87Rb and 85Rb. (b–d) Survival probability P versus time t for the A, B and C collisions, respectively. The measurements are done for the survival probability of 87Rb after kicking out 85Rb. The black squares are experimental data, with each point being the result from 300 repeated measurements. In (b,c) the solid curves show a fit by the formula P=w exp(−t/τ)+w0, and the error in the decay time indicates the s.d. when using the fit of P(t) by the exponential formula. In (d) the solid curve is a fit with the numerical solution of the rate equations including single-atom spin relaxation. The error in the decay time shows the uncertainty originating from the uncertainty in the single atom spin relaxation time τr entering the rate equations (see Methods). The data are collected at the trap depth U0=0.6 mK and the initial temperatures T87=35±3 μK, T85=15±1 μK.
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f2: Experimental data for the decay rates.(a) Energy levels of hyperfine states of 87Rb and 85Rb. (b–d) Survival probability P versus time t for the A, B and C collisions, respectively. The measurements are done for the survival probability of 87Rb after kicking out 85Rb. The black squares are experimental data, with each point being the result from 300 repeated measurements. In (b,c) the solid curves show a fit by the formula P=w exp(−t/τ)+w0, and the error in the decay time indicates the s.d. when using the fit of P(t) by the exponential formula. In (d) the solid curve is a fit with the numerical solution of the rate equations including single-atom spin relaxation. The error in the decay time shows the uncertainty originating from the uncertainty in the single atom spin relaxation time τr entering the rate equations (see Methods). The data are collected at the trap depth U0=0.6 mK and the initial temperatures T87=35±3 μK, T85=15±1 μK.

Mentions: We measure the survival probability P(t) for the atoms to remain in the trap at time t (see Fig. 2). For each t we execute 300 repetitions of the loop sequence of Fig. 1b. In the case of A and B processes the decay is strongly dominated by the interaction-induced spin relaxation. The probability P(t) is then described by an exponential time dependence. Within <10% of uncertainty the experimental data can be fitted with an exponential function P=w exp(−t/τ)+w0. The presence of the offset w0 has several reasons discussed in detail in Methods. First of all, the two-atom system is obtained with 95% probability, and there are traps with only one atom that remains trapped on a much longer timescale (about 11 s (ref. 25)) than the collisional lifetime τ. Second, for the A and C processes doubly polarized pairs (for each atom the spin projection is equal to the spin) can decay only due to weak spin–spin or spin–orbit interactions that may change the spin projection of the pair, and the polarized pairs practically remain stable on the timescale of our experiment. For the B process, however, the doubly polarized pairs efficiently relax due to the channel leading to the formation of 87Rb(F=1) and 85Rb(F=3).


Interaction-induced decay of a heteronuclear two-atom system.

Xu P, Yang J, Liu M, He X, Zeng Y, Wang K, Wang J, Papoular DJ, Shlyapnikov GV, Zhan M - Nat Commun (2015)

Experimental data for the decay rates.(a) Energy levels of hyperfine states of 87Rb and 85Rb. (b–d) Survival probability P versus time t for the A, B and C collisions, respectively. The measurements are done for the survival probability of 87Rb after kicking out 85Rb. The black squares are experimental data, with each point being the result from 300 repeated measurements. In (b,c) the solid curves show a fit by the formula P=w exp(−t/τ)+w0, and the error in the decay time indicates the s.d. when using the fit of P(t) by the exponential formula. In (d) the solid curve is a fit with the numerical solution of the rate equations including single-atom spin relaxation. The error in the decay time shows the uncertainty originating from the uncertainty in the single atom spin relaxation time τr entering the rate equations (see Methods). The data are collected at the trap depth U0=0.6 mK and the initial temperatures T87=35±3 μK, T85=15±1 μK.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4525158&req=5

f2: Experimental data for the decay rates.(a) Energy levels of hyperfine states of 87Rb and 85Rb. (b–d) Survival probability P versus time t for the A, B and C collisions, respectively. The measurements are done for the survival probability of 87Rb after kicking out 85Rb. The black squares are experimental data, with each point being the result from 300 repeated measurements. In (b,c) the solid curves show a fit by the formula P=w exp(−t/τ)+w0, and the error in the decay time indicates the s.d. when using the fit of P(t) by the exponential formula. In (d) the solid curve is a fit with the numerical solution of the rate equations including single-atom spin relaxation. The error in the decay time shows the uncertainty originating from the uncertainty in the single atom spin relaxation time τr entering the rate equations (see Methods). The data are collected at the trap depth U0=0.6 mK and the initial temperatures T87=35±3 μK, T85=15±1 μK.
Mentions: We measure the survival probability P(t) for the atoms to remain in the trap at time t (see Fig. 2). For each t we execute 300 repetitions of the loop sequence of Fig. 1b. In the case of A and B processes the decay is strongly dominated by the interaction-induced spin relaxation. The probability P(t) is then described by an exponential time dependence. Within <10% of uncertainty the experimental data can be fitted with an exponential function P=w exp(−t/τ)+w0. The presence of the offset w0 has several reasons discussed in detail in Methods. First of all, the two-atom system is obtained with 95% probability, and there are traps with only one atom that remains trapped on a much longer timescale (about 11 s (ref. 25)) than the collisional lifetime τ. Second, for the A and C processes doubly polarized pairs (for each atom the spin projection is equal to the spin) can decay only due to weak spin–spin or spin–orbit interactions that may change the spin projection of the pair, and the polarized pairs practically remain stable on the timescale of our experiment. For the B process, however, the doubly polarized pairs efficiently relax due to the channel leading to the formation of 87Rb(F=1) and 85Rb(F=3).

Bottom Line: One of the key quantities is the inelastic relaxation (decay) time when one of the atoms or both are in a higher hyperfine state.This experimental method allows us to single out a particular relaxation process thus provides an extremely clean platform for collisional physics studies.Our results have also implications for engineering of quantum states via controlled collisions and creation of two-qubit quantum gates.

View Article: PubMed Central - PubMed

Affiliation: 1] State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, and Wuhan National Laboratory for Optoelectronics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, China [2] Center for Cold Atom Physics, Chinese Academy of Sciences, Wuhan 430071, China.

ABSTRACT
Two-atom systems in small traps are of fundamental interest for understanding the role of interactions in degenerate cold gases and for the creation of quantum gates in quantum information processing with single-atom traps. One of the key quantities is the inelastic relaxation (decay) time when one of the atoms or both are in a higher hyperfine state. Here we measure this quantity in a heteronuclear system of (87)Rb and (85)Rb in a micro optical trap and demonstrate experimentally and theoretically the presence of both fast and slow relaxation processes, depending on the choice of the initial hyperfine states. This experimental method allows us to single out a particular relaxation process thus provides an extremely clean platform for collisional physics studies. Our results have also implications for engineering of quantum states via controlled collisions and creation of two-qubit quantum gates.

No MeSH data available.


Related in: MedlinePlus