Any-to-any connected cavity-mediated architecture for quantum computing with trapped ions or Rydberg arrays
Joshua Ramette, Josiah Sinclair, Zachary Vendeiro, Alyssa Rudelis, Marko Cetina, and Vladan Vuletic
https://arxiv.org/abs/2109.11551
Quantum Wednesday Journal Club by Nathan Shammah
October 13, 2021
From all-to-all coupling to any-to-any coupling via entanglement heralding.
Two model platforms considered:
Instead of 2D or 3D architectures, modules of 1D+cavity.
20 chains and 500 ions
For Rydberg arrays, arbitrary connectivity for up to 1500 neutral-atom qubits. Rydberg interaction locally.
Gate fidelity and speed limited by local Coulomb operations and state readout, rather than the ion-cavity coupling.
Rb: couple to IR cavity
Yb: magnetically insensitive, metastable nuclear spin states
“Only a few all-to-all connected NISQ devices have been realized”
How about Honeywell? SC qubits? (Puri et al., F. Nori et al.)
[23] M. Cetina, L. N. Egan, C. A. Noel, M. L. Goldman, A. R. Risinger, D. Zhu, D. Biswas, and C. Monroe, Quantum gates on individually-addressed atomic qubits subject to noisy transverse motion (2020), arXiv:2007.06768 [quant- ph].
[35] N. Friis, O. Marty, C. Maier, C. Hempel, M. Holz ̈apfel, P. Jurcevic, M. B. Plenio, M. Huber, C. Roos, R. Blatt, and B. Lanyon, Observation of entangled states of a fully controlled 20-qubit system, PRX 8, 021012 (2018)
[36] I. Pogorelov, T. Feldker, C. D. Marciniak, L. Postler, G. Jacob, O. Krieglsteiner, V. Podlesnic, M. Meth, V. Negnevitsky, M. Stadler, B. Ho ̈fer, C. Wa ̈chter, K. Lakhmanskiy, R. Blatt, P. Schindler, and T. Monz, Compact ion-trap quantum computing demonstrator, PRX Quantum 2, 020343 (2021).
Previous work (all-to-all connectivity)
Engineer gates via optical cavities.
Cons: Susceptible to photon losses. Stringent experimental parameters (cavity F, high-fidelity single-photon sources).
Phase of a reflected photon flips depending on the internal state of atoms coupled to a cavity mode.
Cons: Require high-fidelity single-photon sources.
Nonlocal gates through direct transfers of photons between atoms.
Cons: Cooperativity (C) induces errors that scale as 1/√C.
Previous work (teleported gates)
This scheme uses a teleported gate protocol to avoid a direct coupling of the quantum register to the cavity, protecting the quantum information from the decoherence associated with optical losses.
The transfer is done either using two-photon Raman π pulses with nonzero detuning ∆ to release a photon from A and ab- sorb it at B, or with resonant STIRAP by ramping up ΩA while ramping down ΩB
The scheme is limited primarily by the readout time τ_parallel for system sizes up to a few hundred qubits
Can distribute entanglement between 20 chains compris- ing 500 qubits in an average of 200 μs.
The average nonlocal gate fidelity in the nearest- neighbor architecture degrades with increasing system size due to the increasing number of local SWAP gate errors.
Effect of the non- local gate speed on qubit storage errors in a serial, any- to-any connected system. During each two qubit gate of duration T with qubits of lifetime τ, there is probability NT/τ of a qubit storage error among the N qubits.
The Future:
With hundreds to thousands of fully connected qubits, many more NISQ simulations become feasible.
Conclusions