Time-Reversal-Symmetric Single-Photon Wave Packets for Free-Space Quantum Communication

Abstract

Readout and retrieval processes are proposed for efficient, high-fidelity quantum state transfer between a matter qubit, encoded in the level structure of a single atom or ion, and a photonic qubit, encoded in a time-reversal-symmetric single-photon wave packet. They are based on controlling spontaneous photon emission and absorption of a matter qubit on demand in free space by stimulated Raman adiabatic passage. As these processes do not involve mode selection by high-finesse cavities or photon transport through optical fibers, they offer interesting perspectives as basic building blocks for free-space quantum-communication protocols.PACS numbers: 42.50. Pq,03.67.Bg,42.50.Ct,42.50.Ex High-fidelity quantum state transfer between single photons acting as "flying qubits" and matter qubits, such as atoms or ions, acting as "stationary" memory "qubits" is a crucial process for quantum technological applications. It is an important elementary readout and retrieval process in quantum-communication protocols [1] in which quantum information exchange between distant stationary matter qubits is achieved by photon transport through optical fibers or through free-space channels. Whereas fiber based quantum communication offers advantages for local networks [2] free-space implementations are of special interest for the realization of a future worldwide satellite-based quantum-communication network [3].Motivated by its significance for quantum communication the realization of efficient light matter coupling in free space has been subject of recent experimental [4][5][6] and theoretical [7] investigations. Although efficient, high-fidelity quantum state transfer from a matter qubit to a photonic qubit can be achieved by spontaneous photon emission, realizing the reverse process in free space is a formidable experimental challenge. Exploiting timereversal symmetry it has been shown that almost perfect absorption of a single photon in free space is possible provided the single-photon wave packet has an exponentially growing temporal envelope [7]. An interesting probabilistic method for generating and shaping a single-photon wave packet with an exponentially rising envelope has been developed recently [8,9]. The inherent probabilistic nature of the procedure stems from the usage of a photon source based on spontaneous four-wave mixing [10] and the shaping of the wave packet by using electro-optical amplitude modulation. However, the probabilistic nature of these processes is a disadvantage for applications concerning readout and retrieval processes of quantum information and procedures capable of performing such tasks on demand in a deterministic way are favorable.In fiber and cavity based quantum-communication schemes a proposal to overcome the obstacles of probabilistic photon generation and probabilistic wave packet shaping has been developed by Cirac. et al. [11] and has been implemented experimentally by Ritter et al. [12], recently. In this experiment a laser pulse controls the interaction of a single trapped atom wi...

Input-Output Theory with Quantum Pulses

“…-The formalism presented in this letter provides, in a straightforward manner, a full quantum description of a light pulse reflected by a quantum system into one or more distorted modes. Our theory applies equally well to light and other (dispersion free) carriers of quantum states such as microwaves and surface acoustic waves, considered in recent experiments [11,14,32,[36][37][38][39][40][41] and experimental proposals [10,13,[42][43][44][45][46][47].…”

“…[6]). While expansion of the field state on the continua of one and two-photon states [7,8] may be adequate to describe many processes relevant to quantum information processing [9][10][11][12][13][14], a more general and more tractable theory is desired. Indeed, Itô calculus approaches [15,16] and the so-called Fock master equation [17] permit evaluation of the state of a quantum system which is driven by an incident quantum pulse in a superposition of Fock states.…”

Dissipation-enabled efficient excitation transfer from a single photon to a single quantum emitter

“…A photonic qubit stored in a polarization degree of freedom of a photon wave packet, for example, can be converted to a matter qubit and stored in the atomic level structure of the atom (for the reverse process see [7,8,35]). This can be achieved by using an atom with a level structure depicted in Fig.…”

Optimization of STIRAP-based state transfer under dissipation

“…Due to the advantages of being robust, simple, and efficient, this approach, as well as its theoretical extensions [2][3][4][5][6][7][8][9], have found applications in a variety of physical systems for different tasks (see e.g. [10][11][12][13][14][15][16][17][18] and for a most recent review, see [19]). Most recently, great improvements in the coherent control of solid-state devices has led to remarkable demonstrations of STIRAP in superconducting circuits [20] and NV centers [21][22][23].…”