High-dimensional temporal mode storage and filtering with Raman quantum memory

Temporal modes of photons are field-orthogonal wave packets that span an infinite-dimensional Hilbert space, making them promising carriers for high-dimensional quantum information processing. Efficient storage, filtering, and manipulation of these modes are essential to realize their potential in communication, computation, and metrology. Devices like quantum pulse gates, utilizing frequency conversion in nonlinear materials, have been shown to effectively filter temporal modes [1]. Raman quantum memories, on the other hand, offer the advantage of storing, filtering, and manipulating temporal modes within a single device [2]. In this work, we experimentally demonstrate that a warm-ensemble Raman quantum memory functions as a single-mode filter, capable of storing and filtering high-dimensional temporal modes. Through quantum process tomography, we characterize the storage process and confirm its single-mode nature. Additionally, the stored photons can be retrieved with targeted operations to enable mode conversion and bandwidth conversion. We further show that such single-mode selectivity can be leveraged for frequency super-resolution via mode-selective projective measurements. Our study highlights the potential of Raman quantum memories as versatile tools for high-dimensional quantum information processing and quantum sensing.

[1] V. Ansari et al., Phys. Rev. A 96, 063817 (2017).

[2] J. Nunn et al., Phys. Rev. A 75, 011401 (2007).