Coherent manipulation of noise-protected superconducting artificial atoms in the Lambda scheme

Abstract

We propose a new protocol for the manipulation of a three-level artificial atom in Lambda (Λ) configuration. It allows faithful, selective and robust population transfer analogous to stimulated Raman adiabatic passage (Λ-STIRAP), in last-generation superconducting artificial atoms, where protection from noise implies the absence of a direct pump coupling. It combines the use of a two-photon pump pulse with suitable advanced control, operated by a slow modulation of the phase of the external fields, leveraging on the stability of semiclassical microwave drives. This protocol is a building block for manipulation of microwave photons in complex quantum architectures. Its demonstration would be a benchmark for the implementation of a class of multilevel advanced control procedures for quantum computation and microwave quantum photonics in systems based on artificial atoms. [6][7][8]. These are currently investigated roadmaps towards the design of fault tolerant hardware, i.e. complex quantum architectures minimizing effects of decoherence [9,10]. In this scenario artificial atoms (AAs) are very promising since, compared to their natural counterparts, they allow for a larger degree of integration [11][12][13][14], on-chip tunability, stronger couplings [15] and easier production and detection of signals in the novel regime of microwave quantum photonics [16]. Decoherence due to strong coupling to the solid-state environment [6] is their major drawback. Over the years it has considerably softened [10] yielding last-generation superconducting devices with decoherence times in the range ∼ 1 − 100 µs [2, 4,20].Combining potential advantages of AAs is by no means straightforward. Protection from decoherence often implies strong constraints to available external control, which pose key challenges when larger architectures are considered [14]. In this work we study a simple and paradigmatic example, namely a three-level AA driven by a two-tone electric field in the Lambda (Λ) configuration [ Fig.1(a)]. Implementation of this control scheme in lastgeneration superconducting hardware may in principle benefit from low decoherence, which however is achieved at the expenses of suppressing the direct coupling of the pump field, and of possible limitations of selectivity in addressing specific transitions. In this work we show how to implement an efficient Λ configuration in these conditions, and we propose a dynamical scheme allowing to operate quantum control. This solves the problem raised in the last decade by several theoretical proposals on the implementation of advanced control by a Λ-scheme in AAs [3,[21][22][23][24][25], which still awaits experimental demonstration.Quantum control via a dynamical Λ scheme is very important because it may provide a fundamental building block for processing in complex architectures. Indeed adiabatic evolution may be used to trigger twophoton absorption-emission pumping cycles, which allow for on demand manipulation of individual photons in distributed quantum networks, as proposed in the ...

Stimulated Raman adiabatic passage in physics, chemistry, and beyond

“…A number of well-known quantum three-level effects have been demonstrated recently, e.g., the Autler-Townes effect with phase qubits (Li et al, 2012;Sillanpäa et al, 2009) and transmons (Baur et al, 2009), coherent population trapping with phase qubits (Kelly et al, 2010), and EIT with flux qubits (Abdumalikov et al, 2010). Di Stefano et al (2015Stefano et al ( , 2016; Falci et al (2013); ; Liu et al (2005); Paspalakis and Kylstra (2004); Siewert et al (2006Siewert et al ( , 2009 have proposed designs of threestate systems with superconducting circuits suitable for implementation of STIRAP.…”

Advances in quantum control of three‐level superconducting circuit architectures

“…These difficulties raise the question on whether or not it is possible to find a control solution that gives rise to the same physics as the STIRAP taking advantage of the “ladder” couplings alone. We found that this is indeed possible by employing a two‐photon pump pulse supplemented by a suitable phase‐modulation control . Here we study a version which uses reduced control resources, allowing for one of the couplings being always‐on, We consider a two tone pump field where and .…”

“…This problem can be overcome in several ways, for instance by introducing phase modulated pulses cancelling stray detunings analogous to what is described in § and Ref. []. Actually the multilevel nature of the problem brings an unexpected simplification, since when the three‐level truncation is relaxed, the Stark shifts from higher levels partly compensates , allowing substantial population transfer with no further correction.…”

Quantum Control in Qutrit Systems Using Hybrid Rabi-STIRAP Pulses

“…Various experiments demonstrated already that three-level and multilevel systems can be realized using superconducting circuits based on the Josephson effect [6][7][8][9][10][11][12][13]. Several theoretical proposals addressed the implementation of STIRAP in these devices [14,15], including Cooper pair boxes [16][17][18]. In the case of a transmon [19], STIRAP becomes relevant because the direct transfer of population from the ground state to the second excited state is forbidden in the first order due to a vanishingly small electric dipole moment between these two states.…”