Optimization of Broadband Λ-type Quantum Memory Using Gaussian Pulses

Abstract

We optimize the efficiency of broadband Λ-type quantum memories under the restriction of Gaussian-shape optical fields. We demonstrate an experimentally-simple path to enhancing memory efficiency over a wide range of broadband memory parameters.

Quantum optimal control in quantum technologies. Strategic report on current status, visions and goals for research in Europe

“…State preparation is also at the core of storing quantum information, and QOCT has recently been used to derive protocols for the optimal storage of a single photon by a single intra-cavity atom, achieving the maximal efficiency by partially compensating parasitic losses [247]. Broadband operation of the quantum memory allows for simultaneously realizing high efficiency and high speed which only requires Gaussian pulses with optimally tuned parameters [524]. QOCT combined with a coherent spin-exchange interaction arising from random collisions has been used to derive strategies for high-efficiency storage and retrieval of non-classical light, in order to realize quantum memories with noble-gas spins [324].…”

High-fidelity quantum gates via optimizing short pulse sequences in three-level systems

“…Therefore, at least two different types of weight factors are required for the cost function in the three-level system. In particular, because the objective of this work is to achieve robust quantum gates rather than population transfer, there are many error terms with the same order and we have to classify them first before constructing the cost function, as shown in equation (11). Moreover, to properly optimize the total pulse area for short pulse sequences, we here introduce the third type of weight factor in the three-level system.…”

“…In recent years, there is a growing field of research in utilizing high-dimensional quantum systems for quantum information processing [1][2][3][4][5]. Among them, the three-level system has become a representative and popular candidate for encoding qubit [6][7][8][9][10][11][12][13][14], since temporarily using a third state [15][16][17] can reduce the number of physical entities [18] and improve the fidelity of quantum computations [19][20][21][22][23]. This system allows quantum information to be encoded into two low-energy levels, with the transition being indirectly realized through a high-energy one.…”

All-optical quantum memory

“…5), which is significantly broader than what most atomic memories can support. 11 Another important metric to judge a quantum memory by is the time-bandwidth product, which gives an indication of the network speed a given memory can support (e.g., the number of photons that can be stored in a memory at one time). Our broad bandwidth and competitive storage times give rise to an impressive time-bandwidth product of ∼10 7 , which beats most atomic memories by several orders of magnitude.…”