JPH0459792B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to superconducting soliton devices, and more particularly to soliton devices that couple with solitons and do not couple with anti-solitons.

(Prior Art) Attempts have been made to perform information processing using solitons (single magnetic flux quanta) in Josephson junction transmission lines as information media. A soliton is an elevated magnetic flux quantum well known in the art and is fully described in Japanese Patent Publication No. 17982/1998 and the references cited therein. As explained in these documents, Josephson line (i.e. 1
Josephson junctions that are sufficiently longer than the Josephson penetration length λ _J in the dimension direction can propagate solitons.
A soliton can be generated in the Josephson line by a known method (for example, by inputting a pulse), and can be propagated and accelerated in the Josephson line under the influence of a Lorentzian force due to a bias current in the Josephson line. Can be done.

FIG. 3 is a perspective view of an element for explaining a soliton propagating in a Josephson line. 37 is the upper electrode of the Josefson line, 38 is the barrier, 3
Reference numeral 9 represents the lower electrode of the Josephson line, 40 represents a single magnetic flux quantum (soliton), and 41 represents a circulating current forming the single magnetic flux quantum. A soliton formed in the direction indicated by the arrow in the figure propagates in a fixed direction without changing the direction of its magnetic flux.

Figures 4a and 4b show equivalent circuits of Josephson lines in order to intuitively understand the motion of solitons and anti-solitons. In the figure, 42 is the symbol of a Josephson junction, 43 is a junction capacitance, 44 is a nonlinear resistance, 45 is a Josephson current, 46 to 50 are Josephson junctions, and 51 to
58 represents an inductance, and 59 and 60 represent input terminals. First, it is assumed that a pulse current is input from the input terminal in the direction shown by the solid line. Since the junction 50 is switched and a voltage is generated across the junction 50, current flows through the inductance 54, the junction 49, and the inductance 58 in the direction of the solid line. Then, the junction 49 returns to the superconducting state, and this time the junction 49 becomes a voltage state. Junction 49 switches, creating a voltage across it. By repeating this operation, the circulating current moves from matching 50 to junction 46. Next, assume that a pulse current is input in the direction indicated by the broken line. This time, the circulating current in the direction of the dashed line moves from junction 50 to junction 46. The circulating current in the direction of the solid line and the circulating current in the direction of the broken line form magnetic fluxes in opposite directions. One is called a soliton and the other is called an anti-soliton. You can arbitrarily choose which one to call a soliton.

In order to perform information processing using solitons as information media, a soliton device is required to distinguish between solitons and anti-solitons traveling in a Josephson line to which a bias current is applied, and to selectively connect one soliton to the other. This device allows separating solitons and anti-solitons and controlling the flow of information.

(Problems to be Solved by the Invention) Conventionally, in this type of Josephson line circuit, no soliton device has been proposed that selectively couples only solitons and does not couple with anti-solitons. It is an object of the present invention to provide such a soliton device.

(Means for Solving the Problems) According to the present invention, three Josefson lines each consisting of a first and second electrode and a tunnel barrier sandwiched between them are provided, and among these, the first and second The first electrodes of the Josephson line are connected to each other via a resistance or inductance, the second electrodes are connected to each other via a Josephson junction, and the second electrode is connected to each other via a Josephson junction.
The second electrode of the Josephson line is connected to the first electrode of the third Josephson line through a resistor, and the second electrode of the first Josephson line is connected to the third Josephson line through a resistance or inductance. A soliton device is obtained, which is connected to the second electrode and is characterized in that the third Josephson line is provided with a bias current supply line.

(Function) The present invention combines a Josephson line to which a bias current is applied to a Josephson line on which solitons and anti-solitons run, thereby achieving the following:
It has a function of selectively outputting one of the cyclic currents forming solitons and anti-solitons depending on whether they synergize with the bias current or not.

(Example) Next, an example of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram for explaining an embodiment of the present invention, in which 1 to 3 are first to third Josephson lines, 4 and 5 are inductances, 6 is a resistance,
7 represents a bias current supply line, and 8 represents a Josephson junction.

In the circuit shown in FIG. 1, when a soliton or an anti-soliton is made to run on Josephson lines 1 and 2, one will be selectively coupled, which will be explained using a second equivalent circuit. To run a soliton on a Josephson line, for example, an input terminal may be provided at the end of the line and a pulse voltage may be applied.

In Fig. 2, 9 to 22 are inductances,
23 to 23 are Josephson junctions, 33 is a resistor, 3
4 to 36 represent bias current supply lines. Josephson line 1 in Figure 1 has an inductance of 9.1
0, 14, 15 and Josephson junction 23, 24
corresponds to a circuit composed of Josephson lines 2, inductances 12, 13, 16, 17, and Josephson junctions 27, 28, inductances 4 and 5 are inductances 11 and 18, and resistance 6 is resistance 33. , bias current supply line 7 bias current supply lines 34 to 36, Josephson junction 8 and corresponding Josephson junction. In FIG. 2, the cyclic current shown by the solid line is called a soliton, and the one shown by the broken line is called an anti-soliton. In the process of the soliton traveling from the right to the left, junction 2
6 becomes a voltage state, the junctions 25 and 29 become a voltage state, and in the process of traveling from left to right,
After junction 25 is brought to a voltage state, junctions 26 and 29 are brought to a voltage state. The sign of the voltage appearing at junction 29 is the same in both cases. The junction 29 in the voltage state has the inductance 18 and the junction 29,3
A circulating current is generated in the loop circuit composed of the resistor 33 and the resistor 33 in the direction shown by the solid line, but the bias current 34 puts the junction in a voltage state and the soliton propagates.

On the other hand, in the process in which the aritai soliton travels from right to left, junction 26 becomes voltage state, and then junctions 25 and 29 become voltage state, and in the process in which it travels from left to right, junction 25 becomes voltage state. After reaching the state, junctions 26, 29 are brought to a voltage state. The sign of the voltage appearing at junction 29 is the same in both cases. The junction 29 in the voltage state generates a circulating current in the direction shown by the solid line in the loop circuit composed of the inductance 18, the junctions 29, 30, and the resistor 33. However, since the bias current 34 is in the direction of canceling the circular current, the junction 30 remains superconducting and the circular current remains within the loop circuit. Due to the resistance, the current decays out.

From the above explanation, when the Josephson line 1 and 2 solitons run, a soliton is output to the Josephson line 3, and when the untie soliton runs, there is no output. In addition, in this example,
Although bias current supply lines are not provided in the Josephson lines 1 and 2, they may be provided for accelerating solitons and anti-solitons.

(Effects of the Invention) The present invention provides a soliton device that selectively couples only solitons and does not couple with anti-solitons in Josephson line circuits.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an embodiment of the present invention, FIG. 2 is an equivalent circuit diagram explaining the operating principle of the embodiment,
FIG. 3 is a perspective view illustrating the soliton movement in the Josephson line, and FIGS. 4a and 4b are equivalent circuit diagrams illustrating the soliton movement. 1~3...Jiosefson Railway, 8, 23~3
2,46-50...Josephson junction, 4,5,
9-22, 51-58...Inductance, 6,
33...Resistor, 7, 34-36...Bias current supply line.

Claims (1)

[Claims] 1 Three Josephson lines each consisting of a first and second electrode and a tunnel barrier sandwiched between them are provided, and the first electrodes of the first and second Josephson lines are connected to each other through resistance or inductance. , the second electrodes are connected via a Josephson junction, and the second electrode of the second Josephson line is connected to the first electrode of the third Josephson line via a resistor, and the second electrode of the second Josephson line is connected to the first electrode of the third Josephson line through a resistor. A second electrode of the soliton device is connected to a second electrode of a third Josephson line via a resistance or inductance, and the third Josephson line is provided with a bias current supply line.