We demonstrate controlled pumping of Cooper pairs down to the level of a single pair per cycle, using an rf-driven Cooper-pair sluice. We also investigate the breakdown of the adiabatic dynamics in two different ways. By transferring many Cooper pairs at a time, we observe a crossover between pure Cooper-pair and mixed Cooper-pair-quasiparticle transport. By tuning the Josephson coupling that governs Cooper-pair tunneling, we characterize Landau-Zener transitions in our device. Our data are quantitatively accounted for by a simple model including decoherence effects.We demonstrate controlled pumping of Cooper pairs down to the level of a single pair per cycle, using an rf-driven Cooper-pair sluice. We also investigate the breakdown of the adiabatic dynamics in two different ways. By transferring many Cooper pairs at a time, we observe a crossover between pure Cooper-pair and mixed Cooper-pair-quasiparticle transport. By tuning the Josephson coupling that governs Cooper-pair tunneling, we characterize Landau-Zener transitions in our device. Our data are quantitatively accounted for by a simple model including decoherence effects.

arXiv:1206.0193Physical Review BAug 2, 201218 citations

Probing Cooper Pairs with Pair Transfer

G. Potel, Ricardo A. Broglia

Cambridge University Press eBooksOct 21, 20210 citations

Tunneling of Cooper pairs across voltage-biased asymmetric single-Cooper-pair transistors

Juha Leppäkangas, E. V. Thuneberg, Rene K. Lindell +1 more

We analyze tunneling of Cooper pairs across voltage biased asymmetric single-Cooper-pair transistors. Also tunneling of Cooper pairs across two capacitively coupled Cooper-pair boxes is considered, when the capacitive coupling and Cooper pair tunneling are provided by a small Josephson junction between the islands. The theoretical analysis is done at subgap voltages, where the current-voltage characteristics depend strongly on the macroscopic eigenstates of the island(s) and their coupling to the dissipative environment. As the environment we use an impedance which satisfies $\mathrm{Re}[Z(\ensuremath{\omega})]⪡{R}_{Q}$ and a few $LC$ oscillators in series with $Z(\ensuremath{\omega})$. The numerically calculated $I\text{\ensuremath{-}}V$ curves are compared with experiments where the quantum states of mesoscopic SQUIDs are probed with inelastic Cooper pair tunneling. The main features of the observed $I\text{\ensuremath{-}}V$ data are reproduced. Especially, we find traces of band structure in the higher excited states of the Cooper-pair boxes as well as traces of multiphoton processes between two Cooper-pair boxes in the regime of large Josephson coupling ${E}_{J}⪢{E}_{C}$ .We analyze tunneling of Cooper pairs across voltage biased asymmetric single-Cooper-pair transistors. Also tunneling of Cooper pairs across two capacitively coupled Cooper-pair boxes is considered, when the capacitive coupling and Cooper pair tunneling are provided by a small Josephson junction between the islands. The theoretical analysis is done at subgap voltages, where the current-voltage characteristics depend strongly on the macroscopic eigenstates of the island(s) and their coupling to the dissipative environment. As the environment we use an impedance which satisfies $\mathrm{Re}[Z(\ensuremath{\omega})]⪡{R}_{Q}$ and a few $LC$ oscillators in series with $Z(\ensuremath{\omega})$. The numerically calculated $I\text{\ensuremath{-}}V$ curves are compared with experiments where the quantum states of mesoscopic SQUIDs are probed with inelastic Cooper pair tunneling. The main features of the observed $I\text{\ensuremath{-}}V$ data are reproduced. Especially, we find traces of band structure in the higher excited states of the Cooper-pair boxes as well as traces of multiphoton processes between two Cooper-pair boxes in the regime of large Josephson coupling ${E}_{J}⪢{E}_{C}$.

arXiv:cond-mat/0604092Physical Review BAug 7, 200613 citations

One-dimensional Cooper pairing

Rafael Mendoza, Mauricio Fortes, MANUEL DE LLANO +1 more

arXiv:1008.2970Physica C SuperconductivityJun 26, 20110 citations

Characteristic of single Cooper pair transistor used as sensitive supercurrent sensor

Jutarat Tanarom, Ploybussara Gomasang

The characteristics of the single Cooper pair transistor, a key component of single-charge electronics that manipulates single or Cooper pair electrons via the Coulomb blockade phenomenon, are discussed in this article. Due to these characteristics, the single Cooper pair transistor plays an important role in metrology such as sensitive electrometry and quantum computing. Electron beam lithography and electron gun evaporation are used to fabricate the single Cooper pair transistor. The measurement is performed at lower temperatures than 100 mK by using a dilution refrigerator. It has been found that only the tunneling of Cooper pairs of electrons is shown by the relationship between the gate voltage and the supercurrent. It indicates that a single Cooper pair transistor can be used as a sensitive sensor when integrated into other devices, exhibiting the tunneling properties of Cooper pairs at 16 GHz.The characteristics of the single Cooper pair transistor, a key component of single-charge electronics that manipulates single or Cooper pair electrons via the Coulomb blockade phenomenon, are discussed in this article. Due to these characteristics, the single Cooper pair transistor plays an important role in metrology such as sensitive electrometry and quantum computing. Electron beam lithography and electron gun evaporation are used to fabricate the single Cooper pair transistor. The measurement is performed at lower temperatures than 100 mK by using a dilution refrigerator. It has been found that only the tunneling of Cooper pairs of electrons is shown by the relationship between the gate voltage and the supercurrent. It indicates that a single Cooper pair transistor can be used as a sensitive sensor when integrated into other devices, exhibiting the tunneling properties of Cooper pairs at 16 GHz.

International Conference on Photonics Solutions (ICPS)Feb 19, 20250 citations

LC

oscillators in series with $Z(\ensuremath{\omega})$. The numerically calculated $I\text{\ensuremath{-}}V$ curves are compared with experiments where the quantum states of mesoscopic SQUIDs are probed with inelastic Cooper pair tunneling. The main features of the observed $I\text{\ensuremath{-}}V$ data are reproduced. Especially, we find traces of band structure in the higher excited states of the Cooper-pair boxes as well as traces of multiphoton processes between two Cooper-pair boxes in the regime of large Josephson coupling

{E}_{J}⪢{E}_{C}