Chiral quantum network with giant atoms

Abstract

In superconducting quantum circuits (SQCs), chiral routing quantum information is often realized with the ferrite circulators, which are usually buck, lossy and require strong magnetic fields. To overcome these problems, we propose a novel method to realize chiral quantum networks by exploiting the giant atom effects in SQC platforms. By assuming each coupling point modulated with time, the interaction becomes momentum-dependent, and the giant atoms will chirally emit photons due to interference effects. The chiral factor can approach 1, and both the emission direction and rate can be freely tuned by the modulating signals. We demonstrate that the high-fidelity state transfer between remote giant atoms can be realized. Our proposal can be integrated on the superconducting chip easily, and has the potential to work as a tunable toolbox for quantum information processing in future chiral quantum networks.

Interaction between giant atoms in a one-dimensional structured environment

“…Future work may include extending the model to higher-dimensional structured environments [33,59] and to more elaborate band structures [15]. In particular, engineering the band structure is possible by tuning the hopping rate J between neighboring cavities, which has been shown to lead to nontrivial topological properties [23,49,51,52,54,69]. Moreover, the model could be extended beyond the single-excitation regime to study multiphoton bound states [6,14] and superradiant emission.…”

“…The theoretical treatment presented here is similar to that introduced in Refs. [49,52,58,59], modified to describe a giant atom coupled to a one-dimensional (1D) structured environment (see Fig. 1).…”

“…The poles provide a more accurate profile of the decay rate and highlight the non-Markovianity close to the band edges, as depicted in Fig. 3 We note that the resolvent formalism has been used before in structured environments to study small atoms [59] and chiral emission of giant atoms [49,52]. In this manuscript, we will use it instead to explain the interaction mechanism between two GAs, particularly to examine decoherence-free interaction (Secs.…”

“…It is therefore natural to ask whether there is an advantage, with respect to small atoms, in coupling giant atoms to structured environments. While some recent works have touched upon this question [47][48][49][50][51][52][53][54][55], most of them focused on just a single GA.…”

Giant Atoms in a Synthetic Frequency Dimension

“…Now we turn to consider the case θ ≠ 0, which can be readily achieved by tuning the phase of the coherent external field. In this case, the Hamiltonian (3) becomes asymmetric in momentum space such that the spontaneous emission of the giant atom should be chiral [60]. In particular, the giant atom exhibits almost unidirectional emission when θ ¼ π=2 and N ¼ −3, as shown by the modal excitation probability P m ðtÞ ¼ ja m ðtÞj 2 in Fig.…”