Discerning quantum memories based on electromagnetically-induced-transparency and Autler-Townes-splitting protocols

Abstract

Electromagnetically induced transparency (EIT) and Autler-Townes splitting (ATS) are similar, but different quantum optical phenomena: EIT results from a Fano interference, whereas ATS is described by the AC-Stark effect. Likewise, despite their close resemblance, light-storage techniques based on the EIT memory protocol and the recently-proposed ATS memory protocol (E. Saglamyurek et al. Nature Photonics 12, 2018) are distinct: the EIT protocol relies on adiabatic elimination of absorption, whereas the ATS protocol is based on absorption. In this article, we elaborate on the distinction between EIT and ATS memory protocols through numerical analysis and experimental demonstrations in a cold rubidium ensemble. We find that their storage characteristics manifest opposite limits of the light-matter interaction due to their inherent adiabatic vs. non-adiabatic nature. Furthermore, we determine optimal memory conditions for each protocol and analyze ambiguous regimes in the case of broadband storage, where non-optimal memory implementations can possess characteristics of both EIT and ATS protocols. We anticipate that this investigation will lead to deeper understanding and improved technical development of quantum memories, while clarifying distinctions between the EIT and ATS protocols.

Electromagnetically Induced Transparency in Media with Rydberg Excitons 2: Cross-Kerr Modulation

“…With Rydberg atoms, it has been possible to obtain a large optical nonlinearity at the single photon level and perform many sophisticated quantum optics experiments such as optical Kerr effect or correlated states [ 11 ]. It is expected that the medium of Rydberg excitons is also a fertile area [ 22 , 23 , 32 , 35 , 41 ].…”

“…Because slow light experiments can be performed under Autler–Townes or EIT conditions [ 29 , 30 , 31 ], which are often confused, it should be stressed that in this paper we discuss the case of narrow band operations, for which EIT is the most suitable [ 32 ].…”

Broadband and efficient Quantum Memory Using ac Stark Gradient Echo Memory

“…Following the Eq. 4, we employed the transition dipole matrix of J = 1/2||er||J = 1/2 which is 2.5377 (17).10 −29 C.m and perform summation over all possible |F, m F states [44]. The ac Stark intensity I and detuning ∆ estimated to produce a ∆ bw ∼GHz wide bandwidth memory.…”

Electromagnetically Induced Transparency in Media with Rydberg Excitons 1: Slow Light

“…Słowik et al [ 12 ] theoretically proposed to implement single-qubit gates and a two-qubit controlled not (CNOT) gate operating on polarized photons based on light storage. Recently, a highly efficient quantum memory protocol based on EIT has been experimentally demonstrated for cold rubidium [ 13 ] and cesium atoms [ 14 ]. Experimental evidence of spinor slow light as a quantum memory for two-color qubits in cold rubidium has also been presented [ 15 ].…”