David A. Hanneke

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A new measurement resolves cyclotron and spin levels for a single-electron quantum cyclotron to obtain an electron magnetic moment, given by g/2=1.001 159 652 180 85 (76) [0.76 ppt]. The uncertainty is nearly 6 times lower than in the past, and g is shifted downward by 1.7 standard deviations. The new g, with a quantum electrodynamics (QED) calculation,(More)
Quantum electrodynamics (QED) predicts a relationship between the dimensionless magnetic moment of the electron (g) and the fine structure constant (). A new measurement of g using a one-electron quantum cyclotron, together with a QED calculation involving 891 eighth-order Feynman diagrams, determine ÿ1 ˆ 137:035 999 710 …96† ‰0:70 ppbŠ. The uncertainties(More)
A measurement using a one-electron quantum cyclotron gives the electron magnetic moment in Bohr magnetons, g/2=1.001 159 652 180 73 (28) [0.28 ppt], with an uncertainty 2.7 and 15 times smaller than for previous measurements in 2006 and 1987. The electron is used as a magnetometer to allow line shape statistics to accumulate, and its spontaneous emission(More)
Large-scale quantum information processors must be able to transport and maintain quantum information and repeatedly perform logical operations. Here, we show a combination of all of the fundamental elements required to perform scalable quantum computing through the use of qubits stored in the internal states of trapped atomic ions. We quantified the(More)
Hallmarks of quantum mechanics include superposition and entanglement. In the context of large complex systems, these features should lead to situations as envisaged in the 'Schrödinger's cat' thought experiment (where the cat exists in a superposition of alive and dead states entangled with a radioactive nucleus). Such situations are not observed in(More)
We investigate the dynamics of single and multiple ions during transport between and separation into spatially distinct locations in a multizone linear Paul trap. A single 9Be+ ion in a ~2 MHz harmonic well was transported 370 μm in 8 μs, corresponding to 16 periods of oscillation, with a gain of 0.1 motional quanta. Similar results were achieved for the(More)
The universal quantum computer 1 is a device capable of simulating any physical system 2 and represents a major goal for the field of quantum information science. In the context of quantum information, 'universal' refers to the ability to carry out arbitrary unitary transformations in the system's computational space 3. Combining arbitrary(More)
Attempts at quantum theories of gravity as well as tantalizing astrophysics results suggest a need to examine the stability of fundamental constants with respect to position and time. We have chosen to investigate time-variation of the electron-proton mass ratio (µ), as this dimensionless number is critical to our understanding of fundamental interactions.(More)
Measurements with a one-electron quantum cyclotron determine the electron magnetic moment, given by g/2 = 1.001 159 652 180 73(28)[0.28ppt], and the fine structure constant, α −1 = 137.035 999 084(51)[0.37ppb]. supplemented here with a more complete description of the one-electron quantum cyclotron and the measurement methods, a discussion of the cavity(More)
We describe an extension of single-qubit gate randomized benchmarking that measures the error of multiqubit gates in a quantum information processor. This platform-independent protocol evaluates the performance of Clifford unitaries, which form a basis of fault-tolerant quantum computing. We implemented the benchmarking protocol with trapped ions and found(More)