Center for Metrology and Accreditation

Espoo, Finland

Center for Metrology and Accreditation

Espoo, Finland
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Maisi V.F.,Aalto University | Maisi V.F.,Center for Metrology and Accreditation | Kambly D.,University of Geneva | Flindt C.,University of Geneva | Pekola J.P.,Aalto University
Physical Review Letters | Year: 2014

We employ a single-charge counting technique to measure the full counting statistics of Andreev events in which Cooper pairs are either produced from electrons that are reflected as holes at a superconductor-normal-metal interface or annihilated in the reverse process. The full counting statistics consists of quiet periods with no Andreev processes, interrupted by the tunneling of a single electron that triggers an avalanche of Andreev events giving rise to strongly super-Poissonian distributions. © 2014 American Physical Society.

Pekola J.P.,Aalto University | Saira O.-P.,Aalto University | Maisi V.F.,Aalto University | Maisi V.F.,Center for Metrology and Accreditation | And 5 more authors.
Reviews of Modern Physics | Year: 2013

The control of electrons at the level of the elementary charge e was demonstrated experimentally already in the 1980s. Ever since, the production of an electrical current ef, or its integer multiple, at a drive frequency f has been a focus of research for metrological purposes. This review discusses the generic physical phenomena and technical constraints that influence single-electron charge transport and presents a broad variety of proposed realizations. Some of them have already proven experimentally to nearly fulfill the demanding needs, in terms of transfer errors and transfer rate, of quantum metrology of electrical quantities, whereas some others are currently "just" wild ideas, still often potentially competitive if technical constraints can be lifted. The important issues of readout of single-electron events and potential error correction schemes based on them are also discussed. Finally, an account is given of the status of single-electron current sources in the bigger framework of electric quantum standards and of the future international SI system of units, and applications and uses of single-electron devices outside the metrological context are briefly discussed. © 2013 American Physical Society.

Ulvila V.,University of Helsinki | Phillips C.R.,ETH Zurich | Halonen L.,University of Helsinki | Vainio M.,University of Helsinki | Vainio M.,Center for Metrology and Accreditation
Optics Letters | Year: 2013

We report optical frequency comb generation by a continuous-wave pumped optical parametric oscillator (OPO) without any active modulation. The OPO is configured as singly resonant with an additional nonlinear crystal (periodically poled MgO:LiNbO3) placed inside the OPO for phase mismatched second harmonic generation (SHG) of the resonating signal beam. The phase mismatched SHG causes cascading χ2 nonlinearities, which can substantially increase the effective χ3 nonlinearity in MgO:LiNbO3, leading to spectral broadening of the OPO signal beam via self-phase modulation. The OPO generates a stable 4 THz wide (-30 dB) frequency comb centered at 1.56 μm. © 2013 Optical Society of America.

Vainio M.,University of Helsinki | Vainio M.,Center for Metrology and Accreditation | Halonen L.,University of Helsinki
Optics Letters | Year: 2011

The frequency stability of a cw optical parametric oscillator (cw OPO) near the signal-idler degeneracy has been studied. The strong tendency of a near-degenerate OPO to mode hop has been suppressed by using a bulk Bragg grating as a spectral filter in the OPO cavity. An experimental demonstration of stable parametric oscillation in a single longitudinal mode of the OPO cavity is reported, together with the capability of tuning the signal-idler difference frequency from 1 to 4THz. The OPO has potential use in cw terahertz generation. © 2011 Optical Society of America.

Vainio M.,Center for Metrology and Accreditation | Vainio M.,University of Helsinki | Merimaa M.,Center for Metrology and Accreditation | Halonen L.,University of Helsinki
Optics Letters | Year: 2011

A simple method for absolute-frequency measurements of molecular transitions in the mid-IR region is reported. The method is based on a cw singly resonant optical parametric oscillator (SRO), which is tunable from 3.2 to 3:45 μm. The mid-IR frequency of the SRO is referenced to an optical frequency comb through its pump and signal beams. Sub-Doppler spectroscopy and absolute-frequency measurement of the P(7) transition of the μ3 band of CH4 are demonstrated. © 2011 Optical Society of America.

Saira O.-P.,Aalto University | Kemppinen A.,Center for Metrology and Accreditation | Maisi V.F.,Center for Metrology and Accreditation | Pekola J.P.,Aalto University
Physical Review B - Condensed Matter and Materials Physics | Year: 2012

The achievable fidelity of many nanoelectronic devices based on superconducting aluminum is limited by either the density of residual nonequilibrium quasiparticles n qp or the density of quasiparticle states in the gap, characterized by Dynes parameter γ. We infer upper bounds n qp<0.033μm -3 and γ<1. 6×10 -7 from transport measurements performed on Al/Cu/Al single-electron transistors, improving previous results by an order of magnitude. Owing to efficient microwave shielding and quasiparticle relaxation, a typical number of quasiparticles in the superconducting leads is zero. © 2012 American Physical Society.

Satrapinski A.,Center for Metrology and Accreditation | Novikov S.,Aalto University | Lebedeva N.,Aalto University
Applied Physics Letters | Year: 2013

Precision quantum Hall resistance (QHR) measurements were performed on large-area epitaxial graphene device at temperature T = 1.5 K and at magnetic fields B from 8 T down to 2.5 T, that is much lower than typically used in precision QHR measurement. QHR was measured using cryogenic current comparator resistance bridge with relatively large biasing current Isd = 41 μA to reduce measurement uncertainty. The results showed that at B = 8 T, the relative deviation of Hall resistance from the expected quantized value h/2e2 is within experimental uncertainty of 3.5 parts in 10 8 and remained below 0.35 parts per million (ppm) down to B = 3 T. © 2013 AIP Publishing LLC.

Koski J.V.,Aalto University | Maisi V.F.,Aalto University | Maisi V.F.,Center for Metrology and Accreditation | Sagawa T.,University of Tokyo | Pekola J.P.,Aalto University
Physical Review Letters | Year: 2014

We validate experimentally a fluctuation relation known as generalized Jarzynski equality governing the work distribution in a feedback-controlled system. The feedback control is performed on a single electron box analogously to the original Szilard engine. In the generalized Jarzynski equality, mutual information is treated on an equal footing with the thermodynamic work. Our measurements provide the first evidence of the role of mutual information in the fluctuation theorem and thermodynamics of irreversible processes. © 2014 American Physical Society.

Lassila A.,Center for Metrology and Accreditation
Measurement Science and Technology | Year: 2012

An instrument developed for high accuracy calibration of line scales up to 1.16m is described. The instrument is based on an earlier design from the early 1990s. Since then, in order to improve performance and achieve smaller uncertainty, large portions of software, mechanics and optics have been redesigned and several uncertainty components better characterized. The software has been developed to be less sensitive to imperfections of the line mark. In order to decrease noise and deformation coupling in interferometric measurement, the interferometer operating principle has been designed to use a fibre-coupled laser light, interferometer optics have been improved for better phase adjustment and detection and a differential interferometer principle has been taken into use. In order to minimize the effects due to deformations of the stone table rail with moving heavy carriage, a separate bed has been designed under line scale supports. The bed with fixed differential reflector prevents deformations of the table from affecting the line scale versus interferometer position. The main properties of the instrument are described and an uncertainty estimate is presented. The expanded uncertainty (k = 2) for line distance calibration of high-quality low-thermal-expansion line scale is U = [(4.5nm) 2 + (43×10 9L) 2] where L is the measured length. The results of international comparisons support the uncertainty estimate. © 2012 IOP Publishing Ltd.

Korpelainen V.,Center for Metrology and Accreditation | Seppa J.,Center for Metrology and Accreditation | Lassila A.,Center for Metrology and Accreditation
Precision Engineering | Year: 2010

An interferometrically traceable metrological atomic force microscope (IT-MAFM) has been developed at MIKES. It can be used for traceable atomic force microscope (AFM) measurements and for calibration of transfer standards of scanning probe microscopes (SPMs). Sample position is measured online by 3 axes of laser interferometers. A novel and simple method for detection and online correction of the interferometer nonlinearity was developed. Effect of the nonlinearity in measurements is demonstrated. In the design, special attention has been paid to elimination of external disturbances like electric noise, acoustic noise, ambient temperature variations and vibrations. The instrument has been carefully characterized. The largest uncertainty components are caused by Abbe errors, orthogonality errors, drifts and noise. Noise level in Z direction was 0.25 nm, and in X and Y directions 0.36 nm and 0.31 nm, respectively. Standard uncertainties for X, Y and Z coordinates are u cx = q[0.48; 0.04x; 0.17y; 1.7z; 2 time] nm, ucy = q[0.45; 0.31x; 0.07y; 0.14z; 4 time] nm and ucz = q[0.42; 3x; 7.2y; 0.18z; 2 time] nm where x, y, z are in μm and time in h. Standard uncertainty for 300 nm pitch is 0.023 nm,and for 7 nm step height measurement is 0.35 nm. Uncertainty estimates are supported by an international comparison. © 2010 Elsevier Inc. All rights reserved.

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