Quantum gates with phase stability over space and time

Inlek, I. V.; Vittorini, Grahame; Hucul, David; Crocker, Clayton; Monroe, Christopher

doi:10.1103/physreva.90.042316

Cited by 16 publications

(11 citation statements)

References 32 publications

(39 reference statements)

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“…We assign this to mechanical fluctuations (e.g., fans) that shift the standing wave of the optical Raman beams relative to the ions. This effect can be mitigated by switching to a "phase-insensitive" configuration 57 To investigate the degree to which control errors impact our physical T * 2 qubit decoherence, we perform microwave Ramsey experiments, which are not sensitive to optical beam path fluctuations. Additionally, we suppress magnetic field inhomogeneity using a dynamical decoupling technique that applies π-pulses with alternating 90°phase offsets, commonly known as an (XY ) N pulse sequence 58 , to periodically refocus the qubit spin.…”

Section: Logical T *mentioning

confidence: 99%

Fault-Tolerant Operation of a Quantum Error-Correction Code

Egan,

Debroy,

Noel

et al. 2020

Preprint

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Quantum error correction protects fragile quantum information by encoding it in a larger quantum system whose extra degrees of freedom enable the detection and correction of errors. An encoded logical qubit thus carries increased complexity compared to a bare physical qubit. Fault-tolerant protocols contain the spread of errors and are essential for realizing error suppression with an error-corrected logical qubit. Here we experimentally demonstrate fault-tolerant preparation, rotation, error syndrome extraction, and measurement on a logical qubit encoded in the 9-qubit Bacon-Shor code. For the logical qubit, we measure an average fault-tolerant preparation and measurement error of 0.6% and a transversal Clifford gate with an error of 0.3% after error correction. The result is an encoded logical qubit whose logical fidelity exceeds the fidelity of the entangling operations used to create it. We compare these operations with non-fault-tolerant protocols capable of generating arbitrary logical states, and observe the expected increase in error. We directly measure the four Bacon-Shor stabilizer generators and are able to detect single qubit Pauli errors. These results show that fault-tolerant quantum systems are currently capable of logical primitives with error rates lower than their constituent parts. With the future addition of intermediate measurements, the full power of scalable quantum error-correction can be achieved.

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Section: Logical T *mentioning

confidence: 99%

Fault-Tolerant Operation of a Quantum Error-Correction Code

Egan,

Debroy,

Noel

et al. 2020

Preprint

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show abstract

“…Conversely, the sidebands could be defined around f lower , in which case f upper (as well as the feed forward correction) would be applied to the global beam channel. However, other, more complicated configurations of the MS gate exist [59] that impose different requirements on the lock parameters. These can be handled by frequency locking the two Raman transitions to different harmonics of the frequency comb, which is possible using this hardware.…”

Section: ) Each Raman Transition Consists Of Two Tones Wherementioning

confidence: 99%

Engineering the Quantum Scientific Computing Open User Testbed

Clark

Lobser

Revelle

et al. 2021

IEEE Trans. Quantum Eng.

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The Quantum Scientific Computing Open User Testbed (QSCOUT) at Sandia National Laboratories is a trapped-ion qubit system designed to evaluate the potential of near-term quantum hardware in scientific computing applications for the US Department of Energy (DOE) and its Advanced Scientific Computing Research (ASCR) program. Similar to commercially available platforms, it offers quantum hardware that researchers can use to perform quantum algorithms, investigate noise properties unique to quantum systems, and test novel ideas that will be useful for larger and more powerful systems in the future. However, unlike most other quantum computing testbeds, QSCOUT allows both quantum circuit and low-level pulse control access to study new modes of programming and optimization. The purpose of this manuscript is to provide users and the general community with details of the QSCOUT hardware and its interface, enabling them to take maximum advantage of its capabilities.

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“…The two-qubit gate induced by Raman lasers can be realized in a way that is sensitive to the optical phase of the Raman beams and a way insensitive to the optical phase of the Raman beams [24]. The phase sensitive configuration is realized if the ∆k 1 and ∆k 2 of the bichromatic field inducing the Mølmer and Sørensen gate are parallel.…”

Section: Two-qubit Gate Realization Mølmer-sørensen Interactionmentioning

confidence: 99%

Quantum Graph Analysis

Maunz

Sterk

Lobser

et al. 2016

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In recent years, advanced network analytics have become increasingly important to national security with applications ranging from cyber security to detection and disruption of terrorist networks. While classical computing solutions have received considerable investment, the development of quantum algorithms to address problems, such as data mining of attributed relational graphs, is a largely unexplored space. Recent theoretical work has shown that quantum algorithms for graph analysis can be more efficient than their classical counterparts. Here, we have implemented a trapped-ion-based two-qubit quantum information processor to address these goals. Building on Sandia's microfabricated silicon surface ion traps, we have designed, realized and characterized a quantum information processor using the hyperfine qubits encoded in two 171 Yb + ions. We have implemented single qubit gates using resonant microwave radiation and have employed Gate set tomography (GST) to characterize the quantum process. For the first time, we were able to prove that the quantum process surpasses the fault tolerance thresholds of some quantum codes by demonstrating a diamond norm distance of less than 1.9 × 10 −4. We used Raman transitions in order to manipulate the trapped ions' motion and realize two-qubit gates. We characterized the implemented motion sensitive and insensitive single qubit processes and achieved a maximal process infidelity of 6.5 × 10 −5. We implemented the two-qubit gate proposed by Mølmer and Sørensen and achieved a fidelity of more than 97.7%.

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Quantum gates with phase stability over space and time

Cited by 16 publications

References 32 publications

Fault-Tolerant Operation of a Quantum Error-Correction Code

Fault-Tolerant Operation of a Quantum Error-Correction Code

Engineering the Quantum Scientific Computing Open User Testbed

Quantum Graph Analysis

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