| 1. |
- Batista, P.D., et al.
(författare)
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Acousto-electric single-photon detector
- 2007
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Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. ; 6583, s. 658304-
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Tidskriftsartikel (refereegranskat)abstract
- We propose a novel concept for a semiconductor-based single-photon detector for quantum information processing, which is capable of discriminating the number of photons in a light pulse. The detector exploits the charge transport by a surface acoustic wave (SAW) in order to combine a large photon absorption area (thus providing high photon collection efficiency) with a microscopic charge detection area, where the photo generated charge is detected with resolution at the single electron level using single electron transistors (SETs). We present preliminary results on acoustic transport measured in a prototype for the detector as well as on the fabrication of radio-frequency single-electron transistors (RFSETs) for charge detection. The photon detector is a particular example of acousto-electric nanocircuits that are expected to be able to control both the spatial and the spin degrees of freedom of single electrons. If realized, these circuits will contribute substantially to a scalable quantum information technology.
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| 2. |
- Bauch, Thilo, 1972, et al.
(författare)
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Correlated quantization of supercurrent and conductance in a superconducting quantum point contact
- 2005
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Ingår i: Physical Review B. ; 71:17, s. 174502-
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Tidskriftsartikel (refereegranskat)abstract
- We have measured the supercurrent and conductance of a superconducting quantum point contact in a superconductor two-dimensional electron gas-superconductor Josephson junction. We observe that the supercurrent and conductance change stepwise in a correlated manner as a function of the gate voltage. This was achieved by simultaneous measurement of the supercurrent and conductance at high bias from the same current voltage characteristic.
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| 8. |
- Bylander, Jonas, 1978, et al.
(författare)
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Crossover from time-correlated single-electron tunneling to that of Cooper pairs
- 2007
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Ingår i: Physical Review B. - 2469-9969 .- 2469-9950. ; 76:2, s. 020506(R)-
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Tidskriftsartikel (refereegranskat)abstract
- We have studied charge transport in a one-dimensional chain of small Josephson junctions using a single-electron transistor. We observe a crossover from time-correlated tunneling of single electrons to that of Cooper pairs as a function of both magnetic field and current. At relatively high magnetic field, single-electron transport dominates and the tunneling frequency is given by f=I/e, where I is the current through the chain and e is the electron's charge. As the magnetic field is lowered, the frequency gradually shifts to f=I/2e for I>200 fA, indicating Cooper-pair transport. For the parameters of the measured sample, we expect the Cooper-pair transport to be incoherent.
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| 9. |
- Bylander, Jonas, 1978, et al.
(författare)
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Current measurement by real-time counting of single electrons
- 2005
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 434:7031, s. 361 - 364
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Tidskriftsartikel (refereegranskat)abstract
- The fact that electrical current is carried by individual charges has been known for over 100 years, yet this discreteness has not been directly observed so far. Almost all current measurements involve measuring the voltage drop across a resistor, using Ohm's law, in which the discrete nature of charge does not come into play. However, by sending a direct current through a microelectronic circuit with a chain of islands connected by small tunnel junctions, the individual electrons can be observed one by one. The quantum mechanical tunnelling of single charges in this one-dimensional array is time correlated, and consequently the detected signal has the average frequency f = I/e, where I is the current and e is the electron charge. Here we report a direct observation of these time-correlated single-electron tunnelling oscillations, and show electron counting in the range 5 fA1 pA. This represents a fundamentally new way to measure extremely small currents, without offset or drift. Moreover, our current measurement, which is based on electron counting, is self-calibrated, as the measured frequency is related to the current only by a natural constant.
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| 10. |
- Bylander, Jonas, 1978, et al.
(författare)
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Direct observation of time correlated single-electron tunneling
- 2005
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Ingår i: Conference Program and Extended Abstracts. 10th International Superconductive Electronics Conference. ; , s. O-J.02
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- We report a direct detection of time correlated single-electron tunneling oscillations in a series array of small tunnel junctions. Here the current, I, is made up of a lattice of charge solitons moving throughout the array by time correlated tunneling with the frequency f=I/e, where e is the electron charge. To detect the single charges, we have integrated the array with a radio-frequency single-electron transistor (RF-SET) and employed two different methods to couple the array to the SET input: by direct injection through a tunnel junction, and by capacitive coupling. In this paper we report the results from the latter type of charge input, where we have observed the oscillations in the frequency domain and measured currents from 50 to 250 fA by means of electron counting.
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