Counting Statistics and Dephasing Transition in an Electronic Mach-Zehnder Interferometer

It was recently suggested that a novel type of phase transition may occur in the visibility of electronic Mach-Zehnder Interferometers. Here, we present experimental evidence for the existence of this transition. The transition is induced by strongly non-Gaussian noise that originates from the strong coupling of a quantum point contact to the interferometer. We provide a transparent physical picture of the effect, by exploiting a close analogy to the neutrino-oscillations of particle physics. In addition, our experiment constitutes a probe of the singularity of the elusive full counting statistics of a quantum point contact.Comment: 7 pages, 4 figures (+Supplement 8 pages, 9 figures

Shot noise thermometry of the quantum Hall edge states

We use the non-equilibrium bosonization technique to investigate effects of the Coulomb interaction on quantum Hall edge states at filing factor nu=2, partitioned by a quantum point contact (QPC). We find, that due to the integrability of charge dynamics, edge states evolve to a non-equilibrium stationary state with a number of specific features. In particular, the noise temperature of a weak backscattering current between edge channels is linear in voltage bias applied at the QPC, independently of the interaction strength. In addition, it is a non-analytical function of the QPC transparency T and scales as Tln(1/T) at T<< 1. Our predictions are confirmed by exact numerical calculations.Comment: 5 pages, 3 figure

Санітарний стан соснових деревостанів після проведення санітарних рубок вибіркових, у кулісах та дрібноконтурних ділянках в осередках ураження короїдом верхівковим

During 2017 in Zhytomyr Polissya the sanitary status of pine stands was investigated in the Ips acuminatus pockets after the selective sanitary cuttings, and separately – on the narrow strips and small-plot areas without selective sanitary cuttings. The records, measurements, and descriptions on the study objects were conducted according to generally accepted methods of forestry, forest taxation and forest entomology. It is revealed that the main pest which causes the drying out of studied pine stands was Ips acuminatus. It is demonstrated that in the pine narrow strips and small-plot areas the largest number of studied stands were strongly weakened (58.5 %); drying out – 29.2 %; the weakened – 7.7 %, and the dead – 4.6 %. It should be emphasized that there were no healthy pine stands among studied ones. It was determined that after the selective sanitary cuttings the maximum quota of studied stands were strongly weakened – 42.7 %, which was smaller compared to the corresponding index for the narrow strips and small-plot areas. At the same time, the quota of weakened pine stands was much higher after the selective sanitary cuttings – 21.3 %, and dead – much less (2.7 %) compared to the corresponding index for the narrow strips and small-plot areas. It was concluded that the selective sanitary cuttings in the xylophagous-ophiostomous complex pockets did not not provide the expected effect, and during one or two vegetation periods the sanitary status of pine stands significantly deteriorated, as well as the sanitary status of the pine stands in the narrow strips and small-plot areas. The reasons of this phenomenon are difficulties of diagnosing the affected trees with Ips acuminatus at the initial stage of its infusion and development. The proposal concerning introduction of changes to the current normative documents for forestry management was justified in connection with acute action of xylophagous-ophiostomous complex. As a whole, on our opinion, effective and balanced are Temporary Recommendations for carrying out priority measures in pine forests damaged by bark beetles, developed by a team of scientists of URIFFM under the leadership of prof. V.L. Meshkova. However, entered into force at the same time with the current Sanitary Rules with the higher status, they are not used in the practical forestry of Ukraine.Дослідження проведено у Житомирському Поліссі впродовж 2017 р. Проаналізовано санітарний стан деревостанів сосни звичайної в осередках ураження короїдом верхівковим після проведення санітарних рубок вибіркових (СРВ), а також окремо – у кулісах і дрібноконтурних ділянках. Виявлено, що основним шкідником, який зумовлює всихання досліджених сосняків, є короїд верхівковий. Продемонстровано, що в соснових кулісах та дрібноконтурних ділянках найбільша кількість обстежених деревостанів – сильно ослаблені (58,5 %), всихаючі – 29,2 %, ослаблені – 7,7 % та мертві – 4,6 %. Особливо варто наголосити, що серед досліджуваних сосняків немає здорових деревостанів. Встановлено, що після проведення СРВ максимальна частка сильно ослаблених сосняків становила 42,7 %, що є меншим порівняно з відповідним показником для куліс і дрібноконтурних ділянок. Водночас, частка ослаблених насаджень значно більша після проведення СРВ – 21,3 %, а мертвих – значно менша (2,7 %) порівняно з відповідним показником для куліс та дрібноконтурних ділянок. Зроблено висновок про те, що санітарні рубки вибіркові в осередках ксилофагово-офіостомового комплексу не дають очікуваного ефекту, і за один-два вегетаційні періоди санітарний стан соснових деревостанів значно погіршується, як і санітарний стан сосняків у кулісах та дрібноконтурних ділянках. Обґрунтовано пропозицію про внесення змін у чинні нормативні документи для ведення лісового господарства через гостру дію ксилофагово-офіостомового комплексу

Controlling charge quantization with quantum fluctuations

International audienceIn 1909, Millikan showed that the charge of electrically isolated systems is quantized in units of the elementary electron charge e. Today, the persistence of charge quantization in small, weakly connected conductors allows for circuits where single electrons are manipulated, with applications in e.g. metrology, detectors and thermometry. However, quantum fluctuations progressively reduce the discreteness of charge as the connection strength is increased. Here we report on the full quantum control and characterization of charge quantization. By using semiconductor-based tunable elemental conduction channels to connect a micrometer-scale metallic island, the complete evolution is explored while scanning the entire range of connection strengths, from tunnel barrier to ballistic contact. We observe a robust scaling of charge quantization as the square root of the residual electron reflection probability across a quantum channel when approaching the ballistic critical point, which also applies beyond the regimes yet accessible to theory. At increased temperatures, the thermal fluctuations result in an exponential suppression of charge quantization as well as in a universal square root scaling, for arbitrary connection strengths, in agreement with expectations. Besides direct applications to improve single-electron functionalities and for the metal-semiconductor hybrids emerging in the quest toward topological quantum computing, the knowledge of the quantum laws of electricity will be essential for the quantum engineering of future nanoelectronic devices