Speaker
Description
In this talk, we discuss two directions of scaling up the trapped-ion system for quantum computation and quantum simulation. The first one is to use vibrational degrees of freedom in a linear chain of ions and the second one is to use internal degrees of freedom in the 2D crystals of ions.
Recently, the vibrational degrees of freedom of trapped ions have been extensively studied and are getting more attention [1]. The vibrational modes with phonons can be a good alternative candidate to realize a bosonic network that is able to reveal the advantage of quantum computation by sampling the output distributions. Until now, mostly optical systems have been used to demonstrate boson sampling, but the technical challenges faced in optical systems, such as photon losses, imperfect photon detectors, non-deterministic single-photon generation make it difficult to convincingly demonstrate quantum advantage. However, in the phononic system, the number states can be deterministically prepared and detected and the total number of phonons is well conserved for all the collective modes except the center of mass modes. The main remaining problem is to develop a scalable scheme to realize coherent beam splitters with multiple modes. Here we present the phononic network with up to 4 modes with the capability of the beam splitting operations between any pairs of modes in a programmable way [2]. As the demonstration of the capability of the phononic network, we realized the algorithms of tomography for any multi-modes phononic states in a single measurement configuration [3].
For the second, we present the strong experimental evidence of the quantum simulation by preparing the ground state of the frustrated 2D Ising models through adiabatic evolution. We have developed the 2D crystal of ions in our monolithic Paul trap. In the Paul trap, we have mitigated the micromotion problem of the 2D crystal of ions for the coherent manipulation by applying the propagation direction of Raman laser beams perpendicular to the micromotion direction [4]. In the experiment, we first realize the vibrational ground states of 2D crystals of ions by applying the EIT cooling method [5]. Then we globally apply the spin-dependent force and simultaneously drive the carrier transition to realize the transverse field Ising model [6]. We start the ground state of the transverse field, which slowly ramps down while keeping the Ising spin-spin interactions. We control the character of the spin-spin interactions by changing the detuning of Raman laser beams to various vibrational modes, which result in different ground states of the corresponding spin models [7].
We believe that these examples open the usage of trapped ion systems for large-scale quantum computation and quantum simulation.
[1] Wentao Chen, et al., Chin. Phys. B, 30(6): 060311 (2021).
[2] Wentao Chen, et al., in preparation.
[3] L. Banch, et al., Phys. Rev. Lett.121, 250402 (2018).
[4] Ye Wang, Mu Qiao, et al., Adv. Quant. Techn. 3, 2000068 (2020).
[5] Mu Qiao, et al., Phys. Rev. Lett. 126, 023604 (2021).
[6] Chris Monroe, et al., Rev. Mod. Phys. (2021).
[7] Mu Qiao, et al., in preparation.
