Transport Dynamics of Single Ions in Segmented Microstructured Paul Trap Arrays

Abstract

It was recently proposed to use small groups of trapped ions as qubit carriers in miniaturized electrode arrays that comprise a large number of individual trapping zones, between which ions could be moved [1,2]. This approach might be scalable for quantum information processing with a large numbers of qubits. Processing of quantum information is achieved by transporting ions to and from separate memory and qubit manipulation zones in between quantum logic operations. The transport of ion groups in this scheme plays a major role and requires precise experimental control and fast transport. In this paper we introduce a theoretical framework to study ion transport in external potentials that might be created by typical miniaturized Paul trap electrode arrays. In particular we discuss the relationship between classical and quantum descriptions of the transport and study the energy transfer to the oscillatory motion during near-adiabatic transport. Based on our findings we suggest a numerical method to find electrode potentials as a function of time to optimize the local potential an ion experiences during transport. We demonstrate this method for one specific electrode geometry that should closely represent the situation encountered in realistic trap arrays.

Shortcuts to Adiabaticity

“…In general, a way to avoid spilling or excitation of the atoms is to perform a sufficiently slow (adiabatic) transport, but for many applications the total processing time is limited due to decoherence and an adiabatic transport may turn out to be too long. In the context of quantum information processing, transport could occupy most of the operation time of realistic algorithms, so "transport times" need to be minimized (Reichle et al, 2006;Huber et al, 2008). There are in summary important reasons to reduce the transport time, and several theoretical and experimental works have studied ways to make fast transport also faithful (Couvert et al, 2008a;Murphy et al, 2009;Masuda and Nakamura, 2010;Chen et al, 2010a;Torrontegui et al, 2011Torrontegui et al, , 2012d.…”

Ideal intersections for radio-frequency trap networks

“…Firstly, it has been proposed that transport in a network that is not fully confining can be achieved by "surfing" around any leaks [12]. Secondly, even in the presence of residual a rf field along the network path, it can be possible to perform highly controlled ion transport so that no or minimal heating takes place [8,12]. Nevertheless, it seems that an ideal network would have a number of operational benefits.…”

“…Micromotion is especially arXiv:0802.3162v2 [quant-ph] 19 Jan 2009 critical in trap regions where gate operations are performed [19], but could also potentially lead to heating effects [16]. Secondly, the ponderomotive potential associated with a nonzero rf field along trap paths complicates fully controlled ion transport because the applied control fields must be engineered to compensate for any curvature of U along the path in order to avoid motional heating of the ions [8,12]. Note that such compensation is impossible for the transport of multispecies crystals, which according to Eq.…”

“…In this case, transport as well as splitting and joining of groups of ions have been demonstrated to be possible with a very high degree of control [6,7,8].…”

“…RF traps confine ions by a combination of rf and quasistatic electric fields [4,5] and in an ideal network the rf field and the associated ponderomotive potential vanish in the trapping zones and on dedicated paths between zones but nowhere else. Such ideal trap networks have been demonstrated in one dimension (1D) with segmented linear rf traps where transport as well as splitting and joining of groups of ions have been demonstrated to be possible with a very high degree of control [6,7,8]. In contrast, no ideal 2D trap networks have been identified, although a number of possible intersection geometries for 2D trap networks have been investigated [9,10,11,12,13,14].…”