Research team synchronizes single photons using an atomic quantum memory

A protracted-standing problem within the discipline of quantum physics is the environment friendly synchronization of particular person and independently generated photons (i.e., mild particles). Realizing this might have essential implications for quantum data processing that depends on interactions between a number of photons.

Researchers at Weizmann Institute of Science not too long ago demonstrated the synchronization of single, independently generated photons utilizing an atomic quantum reminiscence working at room-temperature. Their paper, printed in Bodily Evaluation Letters, might open new avenues for the research of multi-photon states and their use in quantum data processing.

“The mission thought took place a number of years in the past, when our group and the group of Ian Walmsley demonstrated an atomic quantum reminiscence with an inverted atomic-level scheme in comparison with the standard reminiscences—the ladder reminiscence, named quick ladder reminiscence (FLAME),” Omri Davidson, one of many researchers who carried out the research, advised Phys.org. “These reminiscences are quick and noise-free, and due to this fact they're helpful for synchronization of single photons.”

Photonic quantum computation and different quantum data protocols depend on the profitable technology of multi-photon states. As most quantum sources employed in analysis to this point are probabilistic, they're unsuitable for producing multi-photon states at an affordable charge.

As a part of their latest research, Davidson and his colleagues got down to discover the potential for realizing these states utilizing an atomic quantum reminiscence, units that may retailer the quantum states of photons whereas retaining the quantum data they carry. Their prediction was that their atomic quantum reminiscence would be capable of retailer probabilistically generated photons and launch them on-demand to generate a multi-photon state.

“The target of the present analysis was to exhibit synchronization of single photons utilizing an impartial room-temperature atomic quantum reminiscence for the primary time,” Davidson stated. “To attain this, we needed to rebuild the reminiscence with a number of enhancements, in addition to to construct a single-photon supply that generates photons that may effectively interface with the reminiscence. Lastly, we have been set to exhibit the precise photon synchronization, which interfaced the photon supply and reminiscence modules, with appropriate management electronics of the experiment.”

FLAME, the quantum reminiscence utilized by the researchers and developed as a part of their earlier analysis, depends on an inverted atomic-level scheme, known as a ladder scheme. In comparison with typical ground-state reminiscences, that are usually gradual and susceptible to noise, FLAME is each quick and noise free, but it could possibly solely retailer data for shorter intervals of time. As velocity and lack of noise are important properties for the synchronization of single photons, their hope was that it could permit them to generate multi-photon quantum states.

“The second benefit of our particular ladder scheme in rubidium atoms, is the small wavelength mismatch of the sign and management light-fields transitions,” Davidson defined. “This permits a comparatively lengthy reminiscence lifetime in comparison with different ladder schemes with a bigger wavelength mismatch, because of the smaller two-photon Doppler broadening. Lastly, we generated the photons utilizing the identical atomic-level construction as our reminiscence, which permits environment friendly coupling of the photons with the reminiscence.”

The various benefits of the workforce’s FLAME reminiscence scheme collectively contributed to the success of their experiment, permitting them to synchronize particular person photons at a excessive charge. Utilizing their atomic quantum reminiscence, they have been capable of retailer and retrieve single photons with an end-to-end effectivity of η_e2e=25% and closing antibunching of g⁽²⁾h=0.023, attaining a charge of greater than 1,000 synchronized photon pairs per second.

G ⁽²⁾ h, or photon antibunching, is a measure of how “single” the one photons are. Good single photons have g⁽²⁾h= 0 , whereas classical mild has g⁽²⁾h= 1. Thus, at g⁽²⁾h= 0.023, the photons synchronized by the researchers stay virtually good single-photons, because of the noise-free operation of the reminiscence.

“We have been capable of synchronize photons which are suitable with atomic methods at excessive charge,” Davidson stated. “Photons which are suitable with atoms are necessary for a lot of photonic quantum data protocols, corresponding to a deterministic two-qubit entangling gate. Earlier photon synchronization demonstrations both used broadband photons which aren't suitable with atomic methods, or photons which are suitable with atomic methods with extraordinarily low charges.”

The photon synchronization charge that Davidson and his colleagues attained of their experiments is greater than 1,000 instances higher than earlier demonstrations utilizing photons which are suitable with atomic methods. Their work opens new avenues for the research of interactions between multi-photon states and atoms, corresponding to so-called deterministic two-photon entangling gates. Sooner or later, it might have precious implications each for the belief of quantum data processing and quantum optics methods.

“We're at present exploring two analysis paths,” Davidson added. “The primary is to realize robust photon-photon interactions with rubidium atoms, in the same system to the one used for synchronization. Reaching this purpose will allow us to exhibit a deterministic entangling gate between the synchronized single-photons.

“These gates are an necessary part in photonic quantum computation, as they permit to scale back the useful resource overhead over at present pursued strategies (referred to as linear-optics quantum computation). Thus far, these gates have been solely demonstrated with chilly atoms setups, and never sizzling atoms, which limits the scalability of those methods.”

Of their subsequent research, Davidson and his colleagues additionally plan to additional develop their FLAME reminiscence, permitting it to retailer a photonic qubit (i.e., a photon in a quantum superposition of two polarization states), moderately than solely storing particular person photons in a single polarization state. This might in the end permit them to carry out quantum computations utilizing photons.