Accelerated Rydberg-EIT quantum memory via shortcuts to adiabaticity

Abstract

Electromagnetically induced transparency (EIT) enables coherent light-matter storage, forming the basis of photonic quantum memories that are essential for scalable quantum networks and distributed quantum computing. However, accelerating the storage process violates the adiabatic condition, resulting in the excitation of the lossy intermediate state and a reduction in writing efficiency. We propose and numerically investigate a high-speed, high-fidelity quantum storage scheme by incorporating a shortcut-to-adiabaticity (STA) technique based on counter-diabatic (CD) driving. By introducing a precisely engineered auxiliary field into a conventional EIT system, our protocol significantly shortens the writing time beyond the conventional adiabatic limit while effectively suppressing the transient population of the lossy intermediate state. Furthermore, our scheme demonstrates strong flexibility in pulse design, remaining effective across different temporal profiles of both the control and signal fields. It also exhibits robustness against imperfections in the CD drive. Even with imperfect single-photon writing and non-ideal Rydberg blockade, the scheme retains clear advantages, maintaining high storage performance and overcoming the intrinsic speed-fidelity trade-off of traditional EIT protocols. These features pave the way for fast and robust quantum devices suitable for high-throughput quantum repeaters and advanced quantum information processing.

Figures (8)

• Figure 1: (a) An ensemble of cold $^{87}\text{Rb}$ atoms is confined in a dipole trap. (b) Relevant atomic level structure illustrating the EIT-based storage and retrieval processes, including the CD driving field. (c) Pulse sequences of the signal, control, and CD fields.
• Figure 2: Population dynamics under different scenarios. (a) Standard pulse sequence with total duration $T=500~\mathrm{ns}$, consisting of a Gaussian probe field and a smoothed rectangular control field. (b) Population dynamics corresponding to the pulse sequence in (a). (c) The same pulse sequence temporally compressed to $T=250~\mathrm{ns}$. (d) Population dynamics corresponding to the pulse sequence in (c), where a clear reduction in transfer fidelity is observed due to the breakdown of adiabatic following. (e) CD pulse sequence at $T=250~\mathrm{ns}$, in which an auxiliary CD drive $\Omega_{\mathrm{CD}}$ (blue curve) is applied in addition to the base pulses. (f) Population dynamics under CD driving, demonstrating the restoration of high-fidelity population transfer. The black dashed curves indicate the instantaneous dark-state fidelity. The parameters used in the simulations are $\Omega_p/2 \pi=0.28$ MHz and $\Omega_c/2 \pi=7$ MHz.
• Figure 3: Comparison of EIT light storage protocols. (a) Conventional scheme with a writing time of 500 ns: (i) Pulse sequence of the input signal field and the control field; (ii) The retrieved output signal field. (b) Conventional scheme with a shorter writing time of 250 ns: (i) Pulse sequence of the input signal field and the control field; (ii) Retrieved output signal field. (c) CD-driven scheme: (i) Pulse sequence with CD driving; (ii) The corresponding retrieved signal field. The parameters used in the simulations are $\Gamma_r=2\pi \times 10$ kHz, $\Gamma=2\pi \times 6$ MHz, $\alpha=5$, $N=500$, and $L=100\,\mu\mathrm{m}$.
• Figure 4: Retrieved output signal fields under the CD driving protocol with varying storage parameters. (a) Output fields for different storage times at a fixed optical depth ($\alpha=5$). Panels (i), (ii), and (iii) correspond to storage times of $t_s=800$ ns, $1500$ ns, and $3000$ ns, respectively. (b) Output fields for different optical depths at a fixed storage time ($t_s=800$ ns). Panels (i), (ii), and (iii) correspond to optical depths of $\alpha=3, 5,$ and $7$, respectively. Other parameters are the same with Fig. \ref{['fig3']}.
• Figure 5: (a,c) Applied pulse sequences composed of a smoothed square control field, a CD drive, and two different Gaussian probe pulses. Panels (a) and (c) correspond to the two probe pulses with different temporal profiles, while the control and CD fields are kept identical. (b,d) Corresponding output probe fields obtained by solving the propagation equations for the pulse sequences shown in (a) and (c), respectively. The insets display the population dynamics of $\ket{G}$, $\ket{E}$, and $\ket{R}$. In addition to pulse parameters, other parameters are the same with Fig. \ref{['fig3']}.