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High efficiency coherent optical memory with warm rubidium vapour.

Hosseini M, Sparkes BM, Campbell G, Lam PK, Buchler BC - Nat Commun (2011)

Bottom Line: Here, we present results from a coherent optical memory based on warm rubidium vapour and show 87% efficient recall of light pulses, the highest efficiency measured to date for any coherent optical memory suitable for quantum information applications.We also show storage and recall of up to 20 pulses from our system.These results show that simple warm atomic vapour systems have clear potential as a platform for quantum memory.

View Article: PubMed Central - PubMed

Affiliation: ARC Centre of Excellence for Quantum Atom Optics, Department of Quantum Science, The Australian National University, Canberra, ACT 0200, Australia.

ABSTRACT
By harnessing aspects of quantum mechanics, communication and information processing could be radically transformed. Promising forms of quantum information technology include optical quantum cryptographic systems and computing using photons for quantum logic operations. As with current information processing systems, some form of memory will be required. Quantum repeaters, which are required for long distance quantum key distribution, require quantum optical memory as do deterministic logic gates for optical quantum computing. Here, we present results from a coherent optical memory based on warm rubidium vapour and show 87% efficient recall of light pulses, the highest efficiency measured to date for any coherent optical memory suitable for quantum information applications. We also show storage and recall of up to 20 pulses from our system. These results show that simple warm atomic vapour systems have clear potential as a platform for quantum memory.

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Control field effect on efficiency and noise.(a) Echo efficiency as a function of storage time. (i, red) Data taken for 3 μs pulse while the control field with power of 370 mW was switched off during the storage time. (ii, blue) Data taken for 2 μs pulse while the control field with power of 290 mW was kept on during the storage time. Error bars indicate the detection error derived from fluctuation of the amplitudes of pulses. (b) Efficiency of photon echoes of a 3 μs pulse as a function of control field power. The solid line is the theoretical predictions taking into account diffusion time of 22 μs, control field-induced scattering and ground state decoherence rate of 2π×3.5 kHz. (c) Variance of the probe field mode measured using heterodyne detection. Curves represent electronic noise (black), shot noise (blue) and noise with the control field switched on (red). Measurements were made with a resolution bandwidth=3 kHz, video bandwidth=30 kHz and five averages. The control beam was filtered out of this measurement using and additional gas cell containing warm 85Rb.
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f4: Control field effect on efficiency and noise.(a) Echo efficiency as a function of storage time. (i, red) Data taken for 3 μs pulse while the control field with power of 370 mW was switched off during the storage time. (ii, blue) Data taken for 2 μs pulse while the control field with power of 290 mW was kept on during the storage time. Error bars indicate the detection error derived from fluctuation of the amplitudes of pulses. (b) Efficiency of photon echoes of a 3 μs pulse as a function of control field power. The solid line is the theoretical predictions taking into account diffusion time of 22 μs, control field-induced scattering and ground state decoherence rate of 2π×3.5 kHz. (c) Variance of the probe field mode measured using heterodyne detection. Curves represent electronic noise (black), shot noise (blue) and noise with the control field switched on (red). Measurements were made with a resolution bandwidth=3 kHz, video bandwidth=30 kHz and five averages. The control beam was filtered out of this measurement using and additional gas cell containing warm 85Rb.

Mentions: Figure 4a(i) shows the efficiency as a function of storage time when the control field is on. Taking into account the signal beam radius of 3 mm and 0.5 Torr Kr buffer gas, one can calculate the diffusion time of the atoms, defined as the time that a fraction 1/e2 of atoms have moved a distance greater than the radius of the signal beam, to be τd=22 μs. This value was fixed in our model allowing us to fit only the ground state decay time, which was determined to be τ0=4 μs corresponding to a decay rate of 2π×40 kHz. This is consistent with the scattering rate of 2π×30 kHz calculated above, from which we conclude that our system is limited in this regime by control-beam-induced scattering.


High efficiency coherent optical memory with warm rubidium vapour.

Hosseini M, Sparkes BM, Campbell G, Lam PK, Buchler BC - Nat Commun (2011)

Control field effect on efficiency and noise.(a) Echo efficiency as a function of storage time. (i, red) Data taken for 3 μs pulse while the control field with power of 370 mW was switched off during the storage time. (ii, blue) Data taken for 2 μs pulse while the control field with power of 290 mW was kept on during the storage time. Error bars indicate the detection error derived from fluctuation of the amplitudes of pulses. (b) Efficiency of photon echoes of a 3 μs pulse as a function of control field power. The solid line is the theoretical predictions taking into account diffusion time of 22 μs, control field-induced scattering and ground state decoherence rate of 2π×3.5 kHz. (c) Variance of the probe field mode measured using heterodyne detection. Curves represent electronic noise (black), shot noise (blue) and noise with the control field switched on (red). Measurements were made with a resolution bandwidth=3 kHz, video bandwidth=30 kHz and five averages. The control beam was filtered out of this measurement using and additional gas cell containing warm 85Rb.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3105315&req=5

f4: Control field effect on efficiency and noise.(a) Echo efficiency as a function of storage time. (i, red) Data taken for 3 μs pulse while the control field with power of 370 mW was switched off during the storage time. (ii, blue) Data taken for 2 μs pulse while the control field with power of 290 mW was kept on during the storage time. Error bars indicate the detection error derived from fluctuation of the amplitudes of pulses. (b) Efficiency of photon echoes of a 3 μs pulse as a function of control field power. The solid line is the theoretical predictions taking into account diffusion time of 22 μs, control field-induced scattering and ground state decoherence rate of 2π×3.5 kHz. (c) Variance of the probe field mode measured using heterodyne detection. Curves represent electronic noise (black), shot noise (blue) and noise with the control field switched on (red). Measurements were made with a resolution bandwidth=3 kHz, video bandwidth=30 kHz and five averages. The control beam was filtered out of this measurement using and additional gas cell containing warm 85Rb.
Mentions: Figure 4a(i) shows the efficiency as a function of storage time when the control field is on. Taking into account the signal beam radius of 3 mm and 0.5 Torr Kr buffer gas, one can calculate the diffusion time of the atoms, defined as the time that a fraction 1/e2 of atoms have moved a distance greater than the radius of the signal beam, to be τd=22 μs. This value was fixed in our model allowing us to fit only the ground state decay time, which was determined to be τ0=4 μs corresponding to a decay rate of 2π×40 kHz. This is consistent with the scattering rate of 2π×30 kHz calculated above, from which we conclude that our system is limited in this regime by control-beam-induced scattering.

Bottom Line: Here, we present results from a coherent optical memory based on warm rubidium vapour and show 87% efficient recall of light pulses, the highest efficiency measured to date for any coherent optical memory suitable for quantum information applications.We also show storage and recall of up to 20 pulses from our system.These results show that simple warm atomic vapour systems have clear potential as a platform for quantum memory.

View Article: PubMed Central - PubMed

Affiliation: ARC Centre of Excellence for Quantum Atom Optics, Department of Quantum Science, The Australian National University, Canberra, ACT 0200, Australia.

ABSTRACT
By harnessing aspects of quantum mechanics, communication and information processing could be radically transformed. Promising forms of quantum information technology include optical quantum cryptographic systems and computing using photons for quantum logic operations. As with current information processing systems, some form of memory will be required. Quantum repeaters, which are required for long distance quantum key distribution, require quantum optical memory as do deterministic logic gates for optical quantum computing. Here, we present results from a coherent optical memory based on warm rubidium vapour and show 87% efficient recall of light pulses, the highest efficiency measured to date for any coherent optical memory suitable for quantum information applications. We also show storage and recall of up to 20 pulses from our system. These results show that simple warm atomic vapour systems have clear potential as a platform for quantum memory.

Show MeSH
Related in: MedlinePlus