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Optics Express

Optics Express

  • Editor: C. Martijn de Sterke
  • Vol. 18, Iss. 6 — Mar. 15, 2010
  • pp: 5825–5830
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High quality anti-relaxation coating material for alkali atom vapor cells

M. V. Balabas, K. Jensen, W. Wasilewski, H. Krauter, L. S. Madsen, J. H. Müller, T. Fernholz, and E. S. Polzik  »View Author Affiliations


Optics Express, Vol. 18, Issue 6, pp. 5825-5830 (2010)
http://dx.doi.org/10.1364/OE.18.005825


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Abstract

We present an experimental investigation of alkali atom vapor cells coated with a high quality anti-relaxation coating material based on alkenes. The prepared cells with single compound alkene based coating showed the longest spin relaxation times which have been measured up to now with room temperature vapor cells. Suggestions are made that chemical binding of a cesium atom and an alkene molecule by attack to the C = C bond plays a crucial role in such improvement of anti-relaxation coating quality.

© 2010 OSA

1. Introduction

Alkali atom vapor cells with anti-relaxation coating are used in many experiments in quantum optics and magnetometry [1

1. D. Budker, D. F. Kimball, S. M. Rochester, V. V. Yashchuk, and M. Zolotorev, “Sensitive magnetometry based on nonlinear magneto-optical rotation,” Phys. Rev. A 62(4), 043403 (2000). [CrossRef]

7

7. J. Cviklinski, J. Ortalo, J. Laurat, A. Bramati, M. Pinard, and E. Giacobino, “Reversible quantum interface for tunable single-sideband modulation,” Phys. Rev. Lett. 101(13), 133601 (2008). [CrossRef] [PubMed]

]. Long relaxation times of atomic polarization are necessary for these experiments, and new coating materials improving the spin relaxation time due to wall collisions “in the dark” (i.e. in the absence of optical pumping or probe light) will in many cases also directly improve the performance of these experiments. For instance, in an atomic quantum memory based on alkali vapor cells the storage time equals the transverse relaxation time T2 in the dark. In atomic magnetometry the sensitivity to magnetic fields (the minimal detectable magnetic field in a given measurement time) scales as1/T2.

Experience with the preparation of traditional paraffin coated cells shows that a special period of “ripening” is needed just after the preparation of the coating [8

8. E. B. Alexandrov, M. V. Balabas, D. Budker, D. English, D. F. Kimball, C.-H. Li, and V. V. Yashchuk, “Light-induced desorption of alkali-metal atoms from paraffin coating,” Phys. Rev. A 66(4), 042903 (2002). [CrossRef]

]. The ripening period is characterized by a permanent increase of atom vapor pressure up to values usually 10-15% below the saturated vapor pressure. We know that during the ripening process the coating material absorbs alkali atoms intensively. Some characteristics of absorption were measured [9

9. M. V. Balabas and S. G. Przhibel’sky, “Kinetics of alkali atom absorption by a paraffin coating,” Chem. Phys. Rep. 4(6), 882–889 (1995).

,10

10. V. Liberman and R. J. Knize, “Relaxation of optically pumped Cs in wall-coated cells,” Phys. Rev. 34(6), 5115–5118 (1986). [CrossRef]

], but a detailed understanding of the mechanism of absorption is not established yet.

An interesting observation on the ripening process was made by performing Raman spectroscopy on paraffin coating material inside a potassium cell [11

11. M. V. Ph. D. Balabas, Thesis (Vavilov’s State Optical Institute), 1995.

]. The spectroscopy was performed twice: just after the cell preparation and one year later. The spectral signature of unsaturated C = C bonds at 1644cm1 was found in the first experiment, while no such line was detected one year later. This suggests that potassium atoms modify the molecules of the coating material during the ripening period with saturation of C = C bonds. Organometallic molecules of the type KCH2(CnH2n)CH3 are the likely reaction products formed during the ripening. As a final result we have a solid solution of organometallic molecules in a saturated hydrocarbon solvent as a chemical model of ripened anti-relaxation coating material. Such organometallic molecules should not give rise to significant extra relaxation of alkali atoms vapor ground state polarization, because these molecules have saturated bonds. An interesting question to address is how the concentration of the solid solution affects the quality of the coating.

2. Experiment and results

To investigate the situation we prepared coated cells with 1-octadecene (CH2=CH(CH2)15CH3) and 1-nonadecene (CH2=CH(CH2)16CH3) from Sigma-Aldrich according to the procedure discussed in [8

8. E. B. Alexandrov, M. V. Balabas, D. Budker, D. English, D. F. Kimball, C.-H. Li, and V. V. Yashchuk, “Light-induced desorption of alkali-metal atoms from paraffin coating,” Phys. Rev. A 66(4), 042903 (2002). [CrossRef]

,11

11. M. V. Ph. D. Balabas, Thesis (Vavilov’s State Optical Institute), 1995.

].

We measured the longitudinal relaxation time T1 and the dark line width G0of the magnetic resonance for cesium cells. T1 in the dark was measured by Franzen’s technique [12

12. W. Franzen, “Spin relaxation of optically aligned rubidium vapor,” Phys. Rev. 115(4), 850–856 (1959). [CrossRef]

], described briefly below. The width (HWHM) G0=1/(2πT2) of the RF-optical double resonance line was measured as a function of light intensity in an actively stabilized magnetic environment at a magnetic field B=3500nT and at a cell temperature of Tcell=22C0. The transverse spin decay rate in the dark is determined by extrapolation to zero RF excitation power and light intensity.

The procedure for the T1 measurement is described in detail in [13

13. M. V. Balabas, M. I. Karuzin, and A. S. Pazgalev, “Experimental investigation of the longitudinal relaxation time of electronic polarization of the ground state of potassium atoms in a cell with an antirelaxation coating on the walls,” JEPT Lett. 70(3), 196–200 (1999).

]. In brief, the relaxation time in Franzen’s technique is inferred from the temporal change S(t) in the absorption of circularly polarized light as a result of a change Δni in the distribution of the populations of the Zeeman sublevels of the ground state due to relaxation transitions between them: S(t)=Δni(t)Wi, where Wi are the relative absorption probabilities for σ± polarized light. To detect the absorption signal the Cs vapor cell under study was placed in a longitudinal magnetic field and optically pumped by circularly polarized light on the D1 line along magnetic field direction. Light from a low noise RF-discharge lamp, spectrally filtered by interference filters, is used for optical pumping and the transmitted pump light is measured as a function of time. Interrupting the pump light path for variable time with an electromechanical shutter (switching time below 8ms), the difference in transmission immediately before and after the dark period is used to determine the decay of the atomic polarization in the dark period. Figure 1
Fig. 1 Typical raw signal obtained with Franzen’s technique.
shows raw photo detector signal registered at 12s dark period. The time scale step is 2ms.

The results of the T1 measurements are presented in Fig. 2
Fig. 2 “Relaxation in the dark” signal with a double exponential fit.
for the case of spherical cesium vapor cells. Cell #1 has 35mm diameter and is coated with the material 1-nonadecene, cell #2 used for comparison has 40mm diameter and is coated with a standard paraffin material [8

8. E. B. Alexandrov, M. V. Balabas, D. Budker, D. English, D. F. Kimball, C.-H. Li, and V. V. Yashchuk, “Light-induced desorption of alkali-metal atoms from paraffin coating,” Phys. Rev. A 66(4), 042903 (2002). [CrossRef]

]. Figure 2 shows the experimental Franzen signal together with a fit to a function S(t) with two exponential decaysS(t)=S1fast[1exp(t/T1fast)]+S1slow[1exp(t/T1slow)]. The fitted parameters are presented for standard coating material and 1-nonadecene in Table 1

Table 1. Fit parameters obtained from Franzen signal

table-icon
View This Table
. The physics of fast and slow relaxation mechanisms is discussed in [14

14. M. T. Graf, D. F. Kimball, S. M. Rochester, K. Kerner, C. Wong, D. Budker, E. B. Alexandrov, M. V. Balabas, and V. V. Yashchuk, “Relaxation of atomic polarization in paraffin-coated cesium vapor cells,” Phys. Rev. A 72(2), 023401 (2005). [CrossRef]

].

The RF-optical double resonance line is detected using circularly polarized light on resonance with the CsD1transition, with an experimental setup shown schematically in Fig. 3
Fig. 3 Sketch of the setup for RF-optical double resonance detection.
. We synchronously detect the unresolved group of Δm=1resonances within the F = 4 manifold of the ground state of Cs atoms. The magnetic field induction is actively stabilized at 3440nT. The light beam is oriented at 300to the direction of the static magnetic field. The dispersion component of the synchronous detection signal is chosen to record the double resonance line. The line width is extracted as half the frequency difference between minima and maxima of the dispersion signal. For further details on setup and procedure we refer to [15

15. E. B. Alexandrov, M. V. Balabas, V. A. Bonch-Bruevich, S. V. Provotorov, and N. N. Yakobson, “Laboratory magnetometer bench,” Instrum. Exp. Tech. 29, 241–243 (1986).

].

Figure 4
Fig. 4 Resonance line width as a function of light intensity.
shows the resonance line width as a function of photocurrent (which is proportional to light intensity) together with a linear fit for the same two cells. The dark resonance line width is given by the resonance line width extrapolated to zero RF-excitation power and light intensity and is found from the fit to be G0=1.2(0.1)Hz for standard coating cell and G0=0.67(0.09)Hz for 1-nonadecene coating cell.

Comparison of the measured parameters for the cell with the 1-nonadecene coating and a cell with almost the same characteristic size and our standard paraffin coating shows tenfold elongation of T1 and 2-fold elongation of T2in the dark in favor of the 1-nonadecene coating. It should be noted that T2 time measurements are sensitive to both dephasing due to wall collisions as well as to residual inhomogeneity of the applied magnetic field.

To test the observed superiority of alkene based anti-relaxation coatings a set of coated cells were prepared with several standard mixtures of alkenes from Chevron-Phillips and their laboratory-made fractions. All cells showed good characteristics. Some fraction of alkenes showed very good temperature behavior, and it was possible to get signals at Tcell100C0 with characteristics only slightly worse than those at room temperature. This opens up for a wide range of coated cells for high temperature and thus high vapor density applications. Detailed results of these experiments will be reported elsewhere. Also, a few potassium and rubidium vapor cells were prepared with the new coating material. Those cells showed also very good characteristics.

3. Conclusion

We prepared vapor cells with high quality anti-relaxation coating based on the alkenes. For a well defined single compound coating material a more detailed description and understanding of alkali atom-coating interaction should be feasible. A good model for a solid solution of organometallic molecules in an alkene solvent could also be helpful to explain the results of light induced atom desorption experiments [18

18. T. Karaulanov, M. Graf, D. English, S. Rochester, Y. Rosen, K. Tsigutkin, D. Budker, E. Alexandrov, M. Balabas, D. Kimball, F. Narducci, S. Pustelny, and V. Yashchuk, “Controlling atomic vapor density in paraffin-coated cells using light-induced atomic desorption,” Phys. Rev. A 79(1), 012902 (2009). [CrossRef]

] and electric-field-induced density changes in coated alkali vapor cells [19

19. D. Jackson Kimball, K. Nguyen, K. Ravi, A. Sharma, V. Prabhudesai, S. Rangwala, V. Yashchuk, M. Balabas, and D. Budker, “Electric-field-induced change of alkali-metal vapor density in paraffin-coated cells,” Phys. Rev. A 79(3), 032901 (2009). [CrossRef]

].

Acknowledgements

The authors thank the members of the Quantop research group for their enthusiastic help and discussion, and the company Chevron-Phillips for support and their material supply. M. Balabas thanks Professor A. V. Baranov for Raman spectroscopy experiments and very helpful discussions. The work was funded by the EU projects QAP, COMPAS and HIDEAS.

References and links

1.

D. Budker, D. F. Kimball, S. M. Rochester, V. V. Yashchuk, and M. Zolotorev, “Sensitive magnetometry based on nonlinear magneto-optical rotation,” Phys. Rev. A 62(4), 043403 (2000). [CrossRef]

2.

V. Acosta, M. P. Ledbetter, S. M. Rochester, D. Budker, D. F. Jackson-Kimball, D. C. Hovde, W. Gawlik, S. Pustelny, J. Zachorowski, and V. Yashchuk, “Nonlinear magneto-optical rotation with frequency-modulated light in the geophysical field range,” Phys. Rev. A 73(5), 053404 (2006). [CrossRef]

3.

D. Budker, D. F. Kimball, S. M. Rochester, and V. V. Yashchuk, “Nonlinear Magneto-optics and Reduced Group Velocity of Light in Atomic Vapor with Slow Ground State Relaxation,” Phys. Rev. Lett. 83(9), 1767–1770 (1999). [CrossRef]

4.

A. Kuzmich, K. Mølmer, and E. S. Polzik, “Spin squeezing in an ensemble of atoms illuminated with squeezed light,” Phys. Rev. Lett. 79(24), 4782–4785 (1997). [CrossRef]

5.

B. Julsgaard, A. Kozhekin, and E. S. Polzik, “Experimental long-lived entanglement of two macroscopic objects,” Nature 413(6854), 400–403 (2001). [CrossRef] [PubMed]

6.

J. F. Sherson, H. Krauter, R. K. Olsson, B. Julsgaard, K. Hammerer, I. Cirac, and E. S. Polzik, “Quantum teleportation between light and matter,” Nature 443(7111), 557–560 (2006). [CrossRef] [PubMed]

7.

J. Cviklinski, J. Ortalo, J. Laurat, A. Bramati, M. Pinard, and E. Giacobino, “Reversible quantum interface for tunable single-sideband modulation,” Phys. Rev. Lett. 101(13), 133601 (2008). [CrossRef] [PubMed]

8.

E. B. Alexandrov, M. V. Balabas, D. Budker, D. English, D. F. Kimball, C.-H. Li, and V. V. Yashchuk, “Light-induced desorption of alkali-metal atoms from paraffin coating,” Phys. Rev. A 66(4), 042903 (2002). [CrossRef]

9.

M. V. Balabas and S. G. Przhibel’sky, “Kinetics of alkali atom absorption by a paraffin coating,” Chem. Phys. Rep. 4(6), 882–889 (1995).

10.

V. Liberman and R. J. Knize, “Relaxation of optically pumped Cs in wall-coated cells,” Phys. Rev. 34(6), 5115–5118 (1986). [CrossRef]

11.

M. V. Ph. D. Balabas, Thesis (Vavilov’s State Optical Institute), 1995.

12.

W. Franzen, “Spin relaxation of optically aligned rubidium vapor,” Phys. Rev. 115(4), 850–856 (1959). [CrossRef]

13.

M. V. Balabas, M. I. Karuzin, and A. S. Pazgalev, “Experimental investigation of the longitudinal relaxation time of electronic polarization of the ground state of potassium atoms in a cell with an antirelaxation coating on the walls,” JEPT Lett. 70(3), 196–200 (1999).

14.

M. T. Graf, D. F. Kimball, S. M. Rochester, K. Kerner, C. Wong, D. Budker, E. B. Alexandrov, M. V. Balabas, and V. V. Yashchuk, “Relaxation of atomic polarization in paraffin-coated cesium vapor cells,” Phys. Rev. A 72(2), 023401 (2005). [CrossRef]

15.

E. B. Alexandrov, M. V. Balabas, V. A. Bonch-Bruevich, S. V. Provotorov, and N. N. Yakobson, “Laboratory magnetometer bench,” Instrum. Exp. Tech. 29, 241–243 (1986).

16.

E. Weiss, “Structure of organo alkali metal complexes and related compounds,” Angew. Chem. Int. Ed. Engl. 32(11), 1501–1523 (1993). [CrossRef]

17.

I. P. Beletskaya, “Organometallic chemistry. Part 2,” Soros’s Educational Journal (in Russ.) 11, 90–95 (1998).

18.

T. Karaulanov, M. Graf, D. English, S. Rochester, Y. Rosen, K. Tsigutkin, D. Budker, E. Alexandrov, M. Balabas, D. Kimball, F. Narducci, S. Pustelny, and V. Yashchuk, “Controlling atomic vapor density in paraffin-coated cells using light-induced atomic desorption,” Phys. Rev. A 79(1), 012902 (2009). [CrossRef]

19.

D. Jackson Kimball, K. Nguyen, K. Ravi, A. Sharma, V. Prabhudesai, S. Rangwala, V. Yashchuk, M. Balabas, and D. Budker, “Electric-field-induced change of alkali-metal vapor density in paraffin-coated cells,” Phys. Rev. A 79(3), 032901 (2009). [CrossRef]

OCIS Codes
(160.4890) Materials : Organic materials
(270.2500) Quantum optics : Fluctuations, relaxations, and noise

ToC Category:
Materials

History
Original Manuscript: December 1, 2009
Revised Manuscript: February 10, 2010
Manuscript Accepted: February 26, 2010
Published: March 9, 2010

Citation
M. V. Balabas, K. Jensen, W. Wasilewski, H. Krauter, L. S. Madsen, J. H. Müller, T. Fernholz, and E. S. Polzik, "High quality anti-relaxation coating material for alkali atom vapor cells," Opt. Express 18, 5825-5830 (2010)
http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-18-6-5825


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References

  1. D. Budker, D. F. Kimball, S. M. Rochester, V. V. Yashchuk, and M. Zolotorev, “Sensitive magnetometry based on nonlinear magneto-optical rotation,” Phys. Rev. A 62(4), 043403 (2000). [CrossRef]
  2. V. Acosta, M. P. Ledbetter, S. M. Rochester, D. Budker, D. F. Jackson-Kimball, D. C. Hovde, W. Gawlik, S. Pustelny, J. Zachorowski, and V. Yashchuk, “Nonlinear magneto-optical rotation with frequency-modulated light in the geophysical field range,” Phys. Rev. A 73(5), 053404 (2006). [CrossRef]
  3. D. Budker, D. F. Kimball, S. M. Rochester, and V. V. Yashchuk, “Nonlinear Magneto-optics and Reduced Group Velocity of Light in Atomic Vapor with Slow Ground State Relaxation,” Phys. Rev. Lett. 83(9), 1767–1770 (1999). [CrossRef]
  4. A. Kuzmich, K. Mølmer, and E. S. Polzik, “Spin squeezing in an ensemble of atoms illuminated with squeezed light,” Phys. Rev. Lett. 79(24), 4782–4785 (1997). [CrossRef]
  5. B. Julsgaard, A. Kozhekin, and E. S. Polzik, “Experimental long-lived entanglement of two macroscopic objects,” Nature 413(6854), 400–403 (2001). [CrossRef] [PubMed]
  6. J. F. Sherson, H. Krauter, R. K. Olsson, B. Julsgaard, K. Hammerer, I. Cirac, and E. S. Polzik, “Quantum teleportation between light and matter,” Nature 443(7111), 557–560 (2006). [CrossRef] [PubMed]
  7. J. Cviklinski, J. Ortalo, J. Laurat, A. Bramati, M. Pinard, and E. Giacobino, “Reversible quantum interface for tunable single-sideband modulation,” Phys. Rev. Lett. 101(13), 133601 (2008). [CrossRef] [PubMed]
  8. E. B. Alexandrov, M. V. Balabas, D. Budker, D. English, D. F. Kimball, C.-H. Li, and V. V. Yashchuk, “Light-induced desorption of alkali-metal atoms from paraffin coating,” Phys. Rev. A 66(4), 042903 (2002). [CrossRef]
  9. M. V. Balabas and S. G. Przhibel’sky, “Kinetics of alkali atom absorption by a paraffin coating,” Chem. Phys. Rep. 4(6), 882–889 (1995).
  10. V. Liberman and R. J. Knize, “Relaxation of optically pumped Cs in wall-coated cells,” Phys. Rev. 34(6), 5115–5118 (1986). [CrossRef]
  11. M. V. Ph. D. Balabas, Thesis (Vavilov’s State Optical Institute), 1995.
  12. W. Franzen, “Spin relaxation of optically aligned rubidium vapor,” Phys. Rev. 115(4), 850–856 (1959). [CrossRef]
  13. M. V. Balabas, M. I. Karuzin, and A. S. Pazgalev, “Experimental investigation of the longitudinal relaxation time of electronic polarization of the ground state of potassium atoms in a cell with an antirelaxation coating on the walls,” JEPT Lett. 70(3), 196–200 (1999).
  14. M. T. Graf, D. F. Kimball, S. M. Rochester, K. Kerner, C. Wong, D. Budker, E. B. Alexandrov, M. V. Balabas, and V. V. Yashchuk, “Relaxation of atomic polarization in paraffin-coated cesium vapor cells,” Phys. Rev. A 72(2), 023401 (2005). [CrossRef]
  15. E. B. Alexandrov, M. V. Balabas, V. A. Bonch-Bruevich, S. V. Provotorov, and N. N. Yakobson, “Laboratory magnetometer bench,” Instrum. Exp. Tech. 29, 241–243 (1986).
  16. E. Weiss, “Structure of organo alkali metal complexes and related compounds,” Angew. Chem. Int. Ed. Engl. 32(11), 1501–1523 (1993). [CrossRef]
  17. I. P. Beletskaya, “Organometallic chemistry. Part 2,” Soros’s Educational Journal (in Russ.) 11, 90–95 (1998).
  18. T. Karaulanov, M. Graf, D. English, S. Rochester, Y. Rosen, K. Tsigutkin, D. Budker, E. Alexandrov, M. Balabas, D. Kimball, F. Narducci, S. Pustelny, and V. Yashchuk, “Controlling atomic vapor density in paraffin-coated cells using light-induced atomic desorption,” Phys. Rev. A 79(1), 012902 (2009). [CrossRef]
  19. D. Jackson Kimball, K. Nguyen, K. Ravi, A. Sharma, V. Prabhudesai, S. Rangwala, V. Yashchuk, M. Balabas, and D. Budker, “Electric-field-induced change of alkali-metal vapor density in paraffin-coated cells,” Phys. Rev. A 79(3), 032901 (2009). [CrossRef]

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