Fast ion swapping for quantum-information processing

Kaufmann, Henning; Ruster, Thomas; Schmiegelow, Christian Tomás; Luda, Marcelo Alejandro; Kaushal, V.; Schulz, J.; Lindenfels, D. von; Schmidt‐Kaler, F.; Poschinger, Ulrich

doi:10.1103/physreva.95.052319

Cited by 59 publications

(52 citation statements)

References 34 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In this approach, quantum algorithms are carried out with multiple ions residing at different trap segments, where different phases are accumulated. These phases have to be taken into account within the computational sequences [43].…”

Section: Discussionmentioning

confidence: 99%

Entanglement-Based dc Magnetometry with Separated Ions

et al. 2017

Self Cite

View full text Add to dashboard Cite

We demonstrate sensing of inhomogeneous dc magnetic fields by employing entangled trapped ions, which are shuttled in a segmented Paul trap. As sensor states, we use Bell states of the type |↑↓ + e iϕ |↓↑ encoded in two 40 Ca + ions stored at different locations. Due to the linear Zeeman effect, the relative phase ϕ serves to measure the magnetic field difference between the constituent locations, while common-mode fluctuations are rejected. Consecutive measurements on sensor states encoded in the S 1/2 ground state and in the D 5/2 metastable state are used to separate an ac Zeeman shift from the linear dc Zeeman effect. We measure magnetic field differences over distances of up to 6.2 mm, with accuracies of around 300 fT, sensitivities down to 12 pT/ √ Hz, and spatial resolutions down to 10 nm. For optimizing the information gain while maintaining a high dynamic range, we implement an algorithm for Bayesian frequency estimation.

show abstract

Section: Discussionmentioning

confidence: 99%

Entanglement-Based dc Magnetometry with Separated Ions

et al. 2017

Self Cite

View full text Add to dashboard Cite

show abstract

“…[29]. For a fluorescence detection time of 1.2 ms, we achieve a measurement fidelity of 99.92% for a single static ion.…”

mentioning

confidence: 90%

“…Technical and methodological improvements will allow for much faster shuttling operations and thus increase the operational speed. In conjunction with feedback operations and fast physical two-ion SWAP gates -which have been realized in our trap with high fidelity [29] -our setup will be extended to a freely programmable quantum computing platform.…”

mentioning

confidence: 99%

Scalable Creation of Long-Lived Multipartite Entanglement

et al. 2017

Self Cite

View full text Add to dashboard Cite

We demonstrate the deterministic generation of multipartite entanglement based on scalable methods. Four qubits are encoded in 40 Ca + , stored in a micro-structured segmented Paul trap. These qubits are sequentially entangled by laser-driven pairwise gate operations. Between these, the qubit register is dynamically reconfigured via ion shuttling operations, where ion crystals are separated and merged, and ions are moved in and out of a fixed laser interaction zone. A sequence consisting of three pairwise entangling gates yields a four-ion GHZ state |ψ = 1 √ 2 (|0000 + |1111 ), and full quantum state tomography reveals a Bell state fidelity of 94.4(3)%. We analyze the decoherence of this state and employ dynamic decoupling on the spatially distributed constituents to maintain 69(5)% coherence at a storage time of 1.1 seconds.The key challenge for the realization of quantum information processing devices which actually outperform classical information technology lies in the scaling to a sufficient complexity, while maintaining high operational fidelities. With trapped ions and superconducting circuits being the leading candidates for scalable highfidelity quantum computing (QC) platforms, few-qubit architectures have been realized [1,2], and elementary quantum algorithms [3,4] as well as fundamental building blocks for quantum error correction [5,6] have been demonstrated. For trapped ions, a possible route to scalability was opened up with the seminal proposal of the quantum CCD [7], where ions are stored in segmented, micro-chip-based radiofrequency traps [8,9] and shuttled between distinct trap sites in order to realize quantum logic operations on selected subgroups of qubits [10][11][12][13][14]. Based on these methods, a complete methods set for QC [15] and a fully programmable two-qubit quantum processor [16] have been shown. It is rather likely that any trapped-ion based large-scale QC architecture [17][18][19] will involve ion shuttling operations. As a benchmark for quantum information processing capabilities, the generation and properties of multipartite entangled states have been studied intensively. On the one hand, generating and maintaining such states lies at the heart of quantum computing, on the other hand large multipartite entangled states represent a resource for the measurement-based approach to QC [20,21]. The first generation of a four-particle Greenberger-Horne-Zeilinger (GHZ) states has been accomplished at a state fidelity of 57% by the NIST group [22] [26] has also been demonstrated, QC generally requires deterministic entanglement generation with capabilities for storage and individual manipulation and readout of the qubits. In this work, we demonstrate the scalable generation of GHZ states of up to four trapped ions. Our method is based on single-qubit rotations, pairwise two-qubit entangling gates and shuttling operations. In analogy to arithmetic-logic-units (ALU) in the von-Neumann computer architecture [19], the computational gate operations are driven by laser beams which are di...

show abstract

“…used to separate qubits in memory from the scattered photons during measurement/preparation. We have omitted the ability to swap ions within the chain as shown in [90,91] and used for calculations in [73] which could improve the overall operation time but would require an additional optimization. Note that an alternative approach would be to use two ion species so the data ions are insensitive to the fluorescence of the measurement ions [92,93], but we avoided this method due to technical issues in shuttling mixed-ion crystals.…”

Section: Mapping the Surface Code To An Ion Chainmentioning

confidence: 99%

Simulating the performance of a distance-3 surface code in a linear ion trap

Trout

Gutiérrez

et al. 2018

New J. Phys.

View full text Add to dashboard Cite

We explore the feasibility of implementing a small surface code with 9 data qubits and 8 ancilla qubits, commonly referred to as surface-17, using a linear chain of 171 Yb+ ions. Two-qubit gates can be performed between any two ions in the chain with gate time increasing linearly with ion distance. Measurement of the ion state by fluorescence requires that the ancilla qubits be physically separated from the data qubits to avoid errors on the data due to scattered photons. We minimize the time required to measure one round of stabilizers by optimizing the mapping of the two-dimensional surface code to the linear chain of ions. We develop a physically motivated Pauli error model that allows for fast simulation and captures the key sources of noise in an ion trap quantum computer including gate imperfections and ion heating. Our simulations showed a consistent requirement of a two-qubit gate fidelity of 99.9% for the logical memory to have a better fidelity than physical two-qubit operations. Finally, we perform an analysis of the error subsets from the importance sampling method used to bound the logical error rates to gain insight into which error sources are particularly detrimental to error correction.

show abstract

Fast ion swapping for quantum-information processing

Cited by 59 publications

References 34 publications

Entanglement-Based dc Magnetometry with Separated Ions

Entanglement-Based dc Magnetometry with Separated Ions

Scalable Creation of Long-Lived Multipartite Entanglement

Simulating the performance of a distance-3 surface code in a linear ion trap

Contact Info

Product

Resources

About