Coherent Diabatic Ion Transport and Separation in a Multizone Trap Array

Bowler, Ryan; Gaebler, John; Lin, Yiheng; Tan, Ting Rei; Hanneke, David; Jost, John D.; Home, Jonathan; Leibfried, D.; Wineland, David J.

doi:10.1103/physrevlett.109.080502

Cited by 247 publications

(299 citation statements)

References 22 publications

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“…The QCCD architecture requires exquisite control of the atomic ion positions during shuttling and may require additional atomic ion species to act as 'refrigerator' ions to quench the excess motion from shuttling operations. 34 Rudimentary versions of the QCCD idea have been employed in many quantum information applications such as teleportation and small quantum algorithms, 9 and recent experiments have shown the reliable, repeatable and coherent shuttling of ion qubits over millimetre distances in microsecond timescales 35,36 and through complex 2D junctions. [37][38][39][40] The QCCD approach will help usher the development of trapped ion quantum computers with perhaps 50-1,000 qubits.…”

Section: Ion Trap Qubits and Wiresmentioning

confidence: 99%

Co-designing a scalable quantum computer with trapped atomic ions

2016

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The first generation of quantum computers are on the horizon, fabricated from quantum hardware platforms that may soon be able to tackle certain tasks that cannot be performed or modelled with conventional computers. These quantum devices will not likely be universal or fully programmable, but special-purpose processors whose hardware will be tightly co-designed with particular target applications. Trapped atomic ions are a leading platform for first-generation quantum computers, but they are also fundamentally scalable to more powerful general purpose devices in future generations. This is because trapped ion qubits are atomic clock standards that can be made identical to a part in 10 15 , and their quantum circuit connectivity can be reconfigured through the use of external fields, without modifying the arrangement or architecture of the qubits themselves. In this forwardlooking overview, we show how a modular quantum computer with thousands or more qubits can be engineered from ion crystals, and how the linkage between ion trap qubits might be tailored to a variety of applications and quantum-computing protocols. Quantum information processors have the potential to perform computational tasks that are difficult or impossible using conventional modes of computing. 1-3 In a radical departure from classical information, the qubits of a quantum computer can simultaneously store bit values 0 and 1, and when measured they probabilistically assume definite states. Many interacting qubits, isolated from their environment, can represent huge amounts of information: there are exponentially many binary numbers that can co-exist, with entangled qubit correlations that can behave as invisible wires between the qubits. Even in the face of Moore's Law, or the doubling in conventional computer power every year or two, the complexity of massively entangled quantum states of just a few hundred qubits can easily eclipse the capacity of classical information processing. 4 There are but a few known applications that exploit this quantum advantage, such as Shor's factoring algorithm, 5 and future quantum information processors will likely be applied to special-purpose applications. On the other hand, a quantum computer has not yet been built; therefore, new quantum applications and algorithms will likely follow from the evolution and capability of quantum hardware.In the 20 years since the advent of Shor's algorithm 5 and the discovery of quantum error correction, 6-8 there has been remarkable progress in demonstrations of entangling quantum gates on o10 qubits in certain physical systems. Current efforts aim to scale to hundreds, thousands or even millions of interacting qubits. Unlike the classical scaling of bits and logic gates, however, large quantum systems are not comparable to the behaviour of just a few qubits. Just because 2 or 4 qubits can be completely controlled with negligible errors does not mean that this system can readily scale to 4100 qubits.In the last few years, two particular quantum hardware platforms have e...

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Section: Ion Trap Qubits and Wiresmentioning

confidence: 99%

Co-designing a scalable quantum computer with trapped atomic ions

2016

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“…State initialization, readout, and quantum logic gates have been demonstrated in several systems with small numbers of trapped ions using various atomic species including 9 Be + , 25 Mg + , 40 Ca + , 43 Ca + , 88 Sr + , 111 Cd + , 137 Ba + , and 171 Yb + . The basic elements of scalable QIP have also been demonstrated in multi-zone trap arrays [7,8].…”

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confidence: 99%

High-Fidelity Universal Gate Set forBe9+Ion Qubits

et al. 2016

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We report high-fidelity laser-beam-induced quantum logic gates on magnetic-field-insensitive qubits comprised of hyperfine states in 9 Be + ions with a memory coherence time of more than 1 s. We demonstrate single-qubit gates with error per gate of 3.8(1) × 10 −5 . By creating a Bell state with a deterministic two-qubit gate, we deduce a gate error of 8(4) × 10 −4 . We characterize the errors in our implementation and discuss methods to further reduce imperfections towards values that are compatible with fault-tolerant processing at realistic overhead.Quantum computers can solve certain problems that are thought to be intractable on conventional computers. An important general goal is to realize universal quantum information processing (QIP), which could be used for algorithms having a quantum advantage over processing with conventional bits as well as to simulate other quantum systems of interest [1][2][3]. For large problems, it is generally agreed that individual logic gate errors must be reduced below a certain threshold, often taken to be around 10 −4 [4][5][6], to achieve fault tolerance without excessive overhead in the number of physical qubits required to implement a logical qubit. This level has been achieved in some experiments for all elementary operations including state preparation and readout, with the exception of two-qubit gates, emphasizing the importance of improving multi-qubit gate fidelities. [7,8]. As various ions differ in mass, electronic, and hyperfine structure, they each have technical advantages and disadvantages. For example, 9 Be + is the lightest ion currently considered for QIP, and as such, has several potential advantages. The relatively light mass yields deeper traps and higher motional frequencies for given applied potentials, and facilitates fast ion transport [9,10]. Light mass also yields stronger laser-induced effective spin-spin coupling (inversely proportional to the mass), which can yield less spontaneous emission error for a given laser intensity [11]. However, a disadvantage of 9 Be + ion qubits compared to some heavier ions such as 40 Ca + and 43 Ca + [12, 13] has been the difficulty of producing and controlling the ultraviolet (313 nm) light required to drive 9 Be + stimulated-Raman transitions. In the work reported here, we use an ion trap array designed for scalable QIP [14] and take advantage of recent technological developments with lasers and optical fibers that improve beam quality and pointing stability. We also implement active control of laser pulse intensities to re- duce errors. We demonstrate laser-induced single-qubit computational gate errors of 3.8(1) × 10 −5 and realize a deterministic two-qubit gate to ideally produce the Bell state |Φ + = 1 √ 2 (|↑↑ + |↓↓ ). By characterizing the effects of known error sources with numerical simulations and calibration measurements, we deduce an entangling gate infidelity or error of = 8(4) × 10 −4 , where = 1 -F, and F is the fidelity. Along with Ref.[13]; these appear to be the highest two-qubit gate fidelitie...

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“…For example by using ultrafast lasers, single qubit gate times as fast as 50 ps have been achieved [37] and two-qubit gate times can in principle be considerably improved [38,39]. Transport in the model is limited to 1 m/s but recent experiments have shown that a transport speed of 40-80 m/s can be achieved while still controlling the quantum states of the ion motion [40,41].…”

Section: Discussionmentioning

confidence: 99%

Comparison of ancilla preparation and measurement procedures for the Steane [[7,1,3]] code on a model ion-trap quantum computer

et al. 2013

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We schedule the Steane [[7,1,3]] error correction on a model ion trap architecture with ballistic transport. We compare the level one error rates for syndrome extraction using the Shor method of ancilla prepared in verified cat states to the DiVincenzo-Aliferis method without verification. The study examines how the quantum error correction circuit latency and error vary with the number of available ancilla and the choice of protocol for ancilla preparation and measurement. We find that with few exceptions the DiVincenzo-Aliferis method without cat state verification outperforms the standard Shor method. We also find that additional ancilla always reduces the latency but does not significantly change the error due to the high memory fidelity.

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Coherent Diabatic Ion Transport and Separation in a Multizone Trap Array

Cited by 247 publications

References 22 publications

Co-designing a scalable quantum computer with trapped atomic ions

Co-designing a scalable quantum computer with trapped atomic ions

High-Fidelity Universal Gate Set forBe9+Ion Qubits

Comparison of ancilla preparation and measurement procedures for the Steane [[7,1,3]] code on a model ion-trap quantum computer

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