ExIQ · Exponentially Improved Quantum memory
Horizon 2020 — Marie Skłodowska-Curie Actions
- Duration
- 2020-06-15 → 2022-06-14
- EU contribution
- €162,806
- Participants
- 1
- Scheme
- MSCA-IF
Lines connect the coordinator with its partners.
Results in brief
Exponentially Improved Quantum memory
The interaction between light and matter is a fundamental process in nature that is relevant for many quantum technologies. A prime example of such potential technologies are quantum memories. As our current IT technology relies on memories to store the information before it is processed — or send around the globe —, quantum technologies will rely heavily on quantum memories. Quantum memories will for example allow to securely communicate over global distances. Hereby, the security of the communication does not depend anymore on the limited resources of the attackers but is given by fundamental laws of physics. During ExIQ, I worked towards the implementation of a new type of quantum memory based on a recent theoretical proposal [1]. This new type of quantum memory relies on the control of quantum interferences. In this context, the phenomenon is called selective radiance and suppresses losses, while enhancing the transfer of information into the desired channel. The work was performed on a platform of cold atoms coupled to a nanofiber. Cold atom setups are system laser cool atoms (Caesium in our experiment) close to the absolute zero (~microkelvins). Under these conditions, the quantum state of each atom can be well controlled, and the atoms are well isolated from the environment. These properties make this technology an ideal candidate to test new theoretical proposals in a well-controlled and clean environment. In our system, quantum emitters (cold atoms) are coupled to a nanofiber via evanescent fields. Our platform allows to efficiently interface emitter in a controlled manner. Thus, it allows us to perform fundamental studies on the interaction between light send through the nanofiber and the coupled quantum emitters. [1] A. Asenjo-Garcia, M. Moreno-Cardoner, A. Albrecht, H. J. Kimble, and D. E. Chang, ‘Exponential Improvement in Photon Storage Fidelities Using Subradiance and ``Selective Radiance’’ in Atomic Arrays’, Phys. Rev. X, vol. 7, no. 3, p. 031024, Aug. 2017
Data: CORDIS, © European Union
Project objective
We plan to demonstrate a new approach towards quantum memories based on a theoretical proposal which is centered around the phenomenon of selective radiance. Selective radiance occurs when the distance between emitters around a waveguide is smaller than the wavelength of the emitters. In this case destructive interference suppresses light scattering into all modes except the forward propagating target mode. This drastically reduces photon losses and increases the efficiency of the quantum memory operation. The error rate of such a new type of quantum memory scales with the optical depth (OD) as exp(-OD) in contrast to the previously established 1/OD. We plan to implement this new scheme with atomic emitters coupled to a nanofiber. Nanofiber based atom-light interfaces are versatile and scalable platforms which allow to precisely study these fundamental quantum effects and at the same time allow for easy integration into fiber based applications. The effect of selective radiance depends upon a lattice with a period smaller than the emitter wavelength. This will be achieved through an appropriate new choice of the laser wavelengths used in the optical trapping scheme. For best memory performance all lattice sites need to be filled. To realize this we use a collisional blockade effect in a Lambda-enhanced gray molasses cooling which ejects one atom every time two or more atoms are present at a lattice site. To optimize the quantum memory performance we will perform an in-depth study of the phenomenon of selective radiance by analyzing the transmission spectrum, the scattering into free space and by ring-down measurements. In the last step we will demonstrate the quantum memory performance and the exponential scaling with OD. The successful demonstration of this type of quantum memory is an important steps towards large distance distribution of quantum information and paves the way for future quantum networks.
Original text from CORDIS.
Participants
- HUMBOLDT-UNIVERSITAET ZU BERLIN · BerlinCoordinatorGermany
Links
Data: CORDIS, © European Union