WO2020239957A1

WO2020239957A1 - Method for designing a superconducting component and associated devices

Info

Publication number: WO2020239957A1
Application number: PCT/EP2020/064921
Authority: WO
Inventors: Eliana RECOBA PAWLOWSKI
Original assignee: Thales
Priority date: 2019-05-28
Filing date: 2020-05-28
Publication date: 2020-12-03
Also published as: FR3096797B1; FR3096797A1

Abstract

The invention relates to a method for designing a superconducting component (40) implemented by a computer comprising a first network (42) of Josephson junctions (52) electrically connected in parallel and having a thickness, the method comprising the following steps: supplying initial input parameters and a required response profile from the component, the input parameters comprising the number and the position of the junctions, the measurement temperature, the value of a power supply current and the initial thickness of each junction, and optimising the component by modifying variable parameters in order to comply with a criterion, which is to minimise the difference in absolute value between the required and computed response profiles, the required response profile being the variation of the voltage output from the component as a function of the variation of an external magnetic field, the variable parameters comprising the thickness of the junctions, the optimising step being implemented by iteration.

Description

Design process for a superconducting component and associated devices

The present invention relates to a method of designing a computer-implemented superconducting component. It also relates to a computer program product, a readable medium and a corresponding superconducting component.

Superconducting components are used in multiple applications including determining the magnetic susceptibilities of tiny samples over a wide temperature range, detecting nuclear magnetic and quadrupole resonance, measuring temperature using noise measurement also called noise thermometry, biomagnetism, geophysics or paleomagnetism.

For this, the Josephson effect is used. By definition, the Josephson effect is manifested by the appearance of a current, also called a supercurrent, between two superconducting materials separated by a non-superconducting layer, for example formed of an insulating material or non-superconducting metal.

Superconducting materials have the particularity of exhibiting zero electrical resistance when their temperature is below a critical temperature. Superconductivity is caused by the formation in material of Cooper pairs, a Cooper pair being formed by the pairing of two electrons. Superconductivity suddenly disappears when the temperature of the material is above the critical temperature.

The non-superconducting layer is called a “barrier layer”. The barrier layer is thin enough so that the Cooper pairs can pass through it, and therefore pass from one superconducting layer to another, by tunneling if the barrier layer is electrically insulating, or by conventional electronic transport otherwise.

The combination of the two superconducting materials and the barrier layer is called a "Josephson junction".

Josephson showed that the difference between the phases of the wave functions on both sides of the Josephson junction is related to the current I of pairs flowing through the barrier and the voltage V across the Josephson junction, by the following relationships :

Or : le is the critical current, which is the maximum direct supercurrent that the Josephson junction can withstand. This critical current is related to the transparency of the barrier and the density of Cooper pairs in the electrodes, and f ₀ is the flux quantum, which is the ratio between Planck's constant and the electric charge of a pair of Cooper.

These relationships make it possible to obtain a characteristic magnetic field - voltage with good sensitivity.

To make the best use of such sensitivity properties of a Josephson junction, and in particular in the field of radiofrequency field detection, it is particularly advantageous to use networks of Josephson junctions. Indeed, connecting the Josephson junctions in parallel in a superconducting component allows to benefit from a better sensitivity for the component compared to a Josephson junction alone.

However, such a network is difficult to polarize given that the current supplying the network is distributed inhomogeneously in the Josephson junctions of the network. Poor polarization of Josephson junctions results in degradation of the properties of the characteristic magnetic field - voltage to which the component is subjected, resulting in degradation of sensitivity.

The inhomogeneous distribution of the currents is even more problematic when the component comprises several networks of parallel Josephson junctions electrically connected in series. This is because the central Josephson junction (s) of the component may not be polarized.

Thus, for a given bias current feeding the component, the Josephson junctions will not all be able to operate at the same time, which does not allow the advantageous effect of the parallel connection of the Josephson junctions to be obtained.

There is therefore a need for a method of designing a superconducting component having an optimized magnetic field - voltage characteristic.

To this end, the present description proposes a method of designing a superconducting component, the method being implemented by computer, the component comprising a first network of Josephson junctions electrically connected in parallel to each other, each Josephson junction having a thickness, the method comprising the steps of: providing initial input parameters of the first network and a required response profile of the superconducting component, the initial input parameters including the number of Josephson junctions, the position of the Josephson junctions, the measurement temperature of the component, the value of a current supply of the component and the initial thickness of each Josephson junction, and optimization of the superconducting component by modifying variable parameters to comply with a criterion comprising at least one sub-criterion, the sub-criterion being to minimize the difference in absolute value between the required response profile and the calculated response profile, the required response profile being the variation of the voltage at the output of the superconducting component as a function of the variation of a magnetic field external to the superconducting component to which said component is subjected and the parameters variables comprising the thickness of one or more Josephson junction (s) of the first network, the optimization step being implemented by iteration, the first iteration taking as a starting point a superconducting component having the initial parameters.

According to particular embodiments, the design method comprises one or more of the following characteristics when this is technically possible:

each Josephson junction comprises a stack of three superimposed layers in a first direction: a first superconducting layer, a second superconducting layer with a barrier layer interposed between the two superconducting layers, for each Josephson junction, the thickness of a Josephson junction being defined as being the thickness of the barrier layer of this Josephson junction measured in the first direction.

- During the optimization step, the thicknesses of at least two Josephson junctions of the first lattice are changed so that at least two Josephson junctions of the designed superconducting component have different thicknesses.

- the thicknesses of the Josephson junctions of the first network having different thicknesses differing by at least 10 nanometers (nm).

- the superconducting component comprises at least a second network of Josephson junctions electrically connected in parallel to each other, the second network being electrically connected in series with the first network, the initial input parameters further include the number of junctions Josephson of the second network and the initial thickness of the Josephson junctions of the second network and, the variable parameters include the thickness of one or more Josephson junction (s) of the first network and / or the second network.

- the superconducting component comprises a plurality of second networks, the superconducting component comprising a total number N of networks, the networks being electrically connected in series to each other, and the method comprises a number of iterations at least equal to the total number N of networks.

- the variable parameters include, in addition, at least one element chosen from the list made up of: the nature of the material (s) forming the Josephson junctions, the position of the Josephson junctions, the measurement temperature, the surfaces of the superconducting loops formed by two Josephson junctions, the assembly of each loop and the two Josephson junctions forming a superconducting quantum interference device, the position of the superconducting loops formed by two Josephson junctions, the assembly of each loop and the two Josephson junctions forming a superconducting quantum interference device (SQUID), the irradiation energy and / or dose of the Josephson junctions when the Josephson junctions are produced by irradiation, the critical current of the Josephson junctions, the resistance of the barrier layers of the Josephson junctions, and the inductance of the superconducting component.

- the required response profile exhibits a characteristic peak having a required amplitude and slope, the optimization step comprising determining the characteristic amplitude and slope of a peak of the response of the superconducting component as a function of the parameters inputs and determining the difference between the required amplitude and the determined amplitude, called the amplitude difference, and the difference between the required slope and the determined slope, called the slope difference.

The description also relates to a method of manufacturing a superconducting component designed according to the design method described above.

Thus, in the manufactured superconducting component, the difference in absolute value between the required response profile and the calculated response profile is minimized.

The description also relates to a computer program product comprising computer program instructions, the computer program instructions being loadable onto a data processing unit and being adapted to cause the implementation of the design method described above. when the computer program product is executed on a data processing unit.

The description also describes a computer readable medium suitable for storing the computer program product described above.

The description also relates to a superconducting component capable of being obtained by implementing the manufacturing method described above. Thus, in the superconducting component, the difference in absolute value between the required response profile and the calculated response profile is minimized.

According to particular embodiments, the component comprises one or more of the following characteristics when this is technically possible:

the superconducting component comprises a required response profile as being the variation of the voltage at the output of the superconducting component as a function of the variation of a magnetic field external to the superconducting component to which said component is subjected, the required response profile exhibiting a peak having a required amplitude and slope, the superconducting component further comprising a calculated response profile having a peak having a calculated amplitude and slope, the calculated response profile of the superconducting component being such that the absolute difference between l The calculated amplitude and the required amplitude is less than or equal to a first tolerance value and that the difference in absolute value between the calculated slope and the required slope is less than or equal to a second tolerance value.

- the first tolerance value is equal to 10% of the required amplitude and the second tolerance value is equal to 10% of the required slope.

The description also describes a superconducting component comprising at least one network of Josephson junctions connected to each other electrically in parallel, at least two Josephson junctions each comprising a different thickness.

Such a difference in thickness of the at least two Josephson junctions corresponds to a difference in thickness greater than the manufacturing tolerances of the manufacturing process of the Josephson junctions. In fact, inherently in the manufacturing process, even aiming to obtain a given thickness, this thickness is only accessible with a manufacturing precision (tolerance) within a range of thicknesses but, despite this variation in thickness, the behaviors of the Josephson junction are unchanged over the entire range of thicknesses. In contrast, in the present context, the behaviors of two Josephson junctions of different thickness are different. Otherwise stated, the thicknesses of two Josephson joints are different if they have two thicknesses sufficiently far from the tolerance values related to the manufacturing process of the Josephson joints or two thicknesses whose thickness ranges have no common point.

According to a particular embodiment, the thicknesses of the at least two Josephson junctions differ from one another by at least 10 nanometers (nm). Other characteristics and advantages of the invention will become apparent on reading the following description of an embodiment of the invention given by way of example only and with reference to the drawings which are:

- Figure 1, a schematic representation of an example of a system allowing the implementation of a design process for a superconducting component;

- Figure 2, a graph showing the characteristic magnetic field - voltage of a superconducting component;

- Figure 3, a schematic representation of a superconducting component;

- Figure 4, a schematic representation of a superconducting component comprising Josephson junctions of varying thicknesses;

- Figure 5, a graph showing a magnetic field - voltage response of a superconducting component;

- Figure 6, a graph showing another magnetic field - voltage response of a superconducting component;

- Figure 7, a graph showing a magnetic field - voltage response of a superconducting component comprising Josephson junctions of identical thickness, and

- Figure 8, a schematic representation of a superconducting component according to another example.

A system 10 and a computer program product 12 are shown in Figure 1. The interaction of the computer program product 12 with the system 10 enables a method of designing a superconducting component to be implemented.

More generally, the system 10 is an electronic computer suitable for handling and / or transforming data represented as electronic or physical quantities in computer registers and / or memories into other similar data corresponding to physical data in memories. registers or other types of display, transmission or storage devices.

System 10 includes a processor 14 including a data processing unit 16, memories 18, and an information medium reader 20. System 10 also includes a keyboard 22 and a display unit 24.

The computer program product 12 includes a readable information medium.

A readable information medium is a medium which can be read by the system 10, usually by the reader 20. The readable information medium is a medium suitable for memorize electronic instructions and capable of being coupled to a bus of a computer system.

By way of example, the readable information medium is a floppy disk or flexible disk (the English name of "Floppy Disc"), an optical disk, a CD ROM, a magnetic disk, a ROM memory, a RAM memory, EPROM memory, EEPROM memory, magnetic card or optical card. A computer program including program instructions is stored on the readable information medium.

The computer program product 12 is loadable on the data processing unit 16 and is adapted to drive the implementation of the design method.

The operation of the system 10 in interaction with the computer program product 12 is now described with reference to an exemplary implementation of a method for designing a superconducting component.

The design process aims to obtain a superconducting component exhibiting improved properties.

More particularly, the design process aims to obtain a superconducting component exhibiting a voltage - magnetic field characteristic providing good sensitivity.

As visible in Figure 2, the voltage - magnetic field characteristic of a superconducting component exhibits an anti-resonant peak 30. Peak 30 is characterized by two magnitudes: the peak-to-peak amplitude of peak 30 denoted AV (shown by the double arrow 32) as well as by the slope halfway up the peak 30 denoted P (represented by the double arrow 34). Peak 30 is a peak characteristic of the voltage-magnetic field characteristic of the superconducting component considered.

As an order of magnitude, the peak-to-peak amplitude of peak 30 is on the order of a few millivolts (mV), for example 2.5 mV.

For the slope P, values of the order of several hundred Volts (V) per Tesla (T) are possible, for example 450 V / T.

The aim of the method is to design components with an improved voltage - magnetic field characteristic at least on one of the elements characterizing peak 30.

The method is a method of optimizing certain parameters characterizing a superconducting component. Such parameters are referred to as variable parameters.

Before explaining these variable parameters, it is appropriate to detail with reference to FIG. 3 the various parameters characterizing a superconducting component 40 which is the object of the optimization. The superconducting component 40 of Figure 3 comprises an array 42 of Josephson junctions and a current supply 46.

A first direction is defined, symbolized in Figure 3 by an X axis. The first direction is therefore designated by the expression "first direction X" in the remainder of the description.

A second direction is also defined as being perpendicular to the first direction X and contained in the figure plane. The second direction is symbolized in Figure 3 by a Y axis. The second direction is therefore designated by the expression "second Y direction" in the remainder of the description.

A third direction is also defined, defined as being perpendicular to the first direction X and the second direction Y. The third direction is symbolized in the figures by an axis Z. The third direction is therefore designated by the expression "third direction Z" in the rest of the description.

Network 42 includes an input terminal 48, an output terminal 50, and a plurality of Josephson junctions 52.

Entry terminal 48 runs along the second Y direction.

In this example, the center O of the XYZ mark is located at the center of the input terminal 48.

The output terminal 50 also extends along the second Y direction.

The network 42 comprises at least two Josephson junctions 52.

Josephson junctions 52 are connected in parallel between input terminal 48 and output terminal 50, each in a branch 54 extending along the second Y direction.

The branches 54 are connected at one end to the input terminal 48 by a first track 58 extending in the second direction Y and at another end by an output terminal 50 by a second track 60 also extending along the line. second direction Y.

Also, each Josephson junction 52 of the network 42 has a defined position. The position of each of the Josephson junctions 52 is defined by a spatial coordinate varying along the second direction Y from the center O of the reference frame XYZ.

It should be noted that the set of each loop formed by two successive Josephson junctions 52 and the two Josephson junctions 52 form a SQUID component (acronym for "Superconducting Quantum Interference Device" in English which literally means in French "superconducting interference device. quantum ") or an SQIF component (acronym for" Superconducting Quantum Interference Filter " in English which literally means in French "Superconducting quantum interference filter").

According to the example of Figure 3, the number of Josephson junctions 52 is equal to 1 1.

For example, the network 42 includes between 10 and 5000 Josephson junctions.

The maximum number of Josephson junctions of the network 42 is given by the technological process.

For example, the first network 42 comprises at least 241 Josephson junctions 52 in parallel. In this case, the length of the network 42 in the second direction Y is 3 millimeters (mm).

On a two-inch wafer (two inches being equal to 50.8 mm), the first array 42 includes up to 4080 junctions in parallel. This number can be further increased by decreasing the size of the SQUIDs or by using a 4 inch wafer (4 inches being equal to 101.6 mm).

In practice, it is desirable to have a component 40 having as many Josephson junctions 52 as possible operating in parallel in order to have increased sensitivity, especially compared to two Josephson junctions in parallel.

Each Josephson junction 52 is a stack of three superimposed layers in the first X direction: a first superconducting layer, a second superconducting layer with a barrier layer interposed between the two superconducting layers.

Structurally, according to the proposed example, each Josephson junction 52 is identical to the others except for a thickness parameter.

By definition, the thickness of a Josephson junction 52 is defined as the thickness of the barrier layer of the considered Josephson junction 52.

The thickness of the barrier layer is measured in the first direction X.

Power supply 46 is electrically connected to input terminal 48.

The current supply 46 is suitable for delivering a current l _p which separates in each branch 54. The current lp is also known under the name “bias current”.

In particular, the current l _p is intended to flow in the first direction X and to pass through the thickness of the Josephson junction 52 along its entire length. The length of the Josephson junction 52 is measured along the first X direction.

The parameters to potentially be considered in the optimization are the parameters having an influence on the characteristic magnetic field - voltage.

Many parameters can be envisaged depending on the description chosen for the magnetic field - voltage characteristic. Indeed, the same physical phenomenon can be described by a first set of parameters or a second set of parameters, the parameters of the second set of parameters being able to be deduced from the parameters of the first set of parameters.

As part of this optimization, the applicant has performed a sorting among the parameters involved in the operation of the superconducting component 40 to select the following parameters:

- the critical current of each Josephson junction 52;

- the measurement temperature;

- the characteristic voltage of each Josephson 52 junction,

- the thickness of each Josephson junction 52,

- the position of each Josephson 52 junction,

- the value of the supply current of the power supply 46,

- the nature of the material (s) forming the Josephson 52 junctions,

- the energy and the irradiation dose of the Josephson 52 junctions when the Josephson junctions are produced by irradiation,

- the resistance of the barrier layer of each Josephson junction 52,

- the height of the Josephson 52 junctions,

- the dimension of the branches 54 of the Josephson junctions 52 measured along the second direction Y,

- the surfaces of the superconducting loops formed by two successive Josephson 52 junctions,

- the position of the surfaces of superconducting loops in the network 42, and

- the inductance of component 40.

Some of the aforementioned parameters are detailed in the remainder of the description.

The critical current is the maximum direct supercurrent that the Josephson junction 52 can withstand. This critical current is related to the transparency of the barrier layer and to the density of Cooper pairs in the electrodes. The critical current is obtained from the measured current-voltage characteristics. We adjust the electrical model RSJ (acronym for "Resistively Shunted Junction" in English which means in French "Resistively shunted junction") to the measurements in order to extract the critical current.

The RSJ model is an electrical model which allows a Josephson junction to be described in the form of equivalent electrical components. Such a model makes it possible to integrate a Josephson junction in an electrical circuit according to the equations which describe the electrical behavior of the junction. Usually we also speak of “RCSJ model” (acronym for “Resistively and Capacitively Shunted Junction” in English which means in French “Junction shuntée resistively and capacitively). In the case of irradiated Josephson junctions, the capacitive effects are negligible and the RSJ (neglected capacitance) model is used.

It will be noted, without going into detail, that the critical current is a function of the component of the magnetic field in a plane transverse to the direction of stacking of the layers of the Josephson junction 52.

In the case of an irradiated Josephson junction 52, the critical current depends on the thickness of the Josephson junction 52, the irradiation dose and the material forming the barrier layer.

The measurement temperature of the superconducting component 40 is the temperature inside the cryostat to which the superconducting component 40 is subjected.

The characteristic voltage of each Josephson junction 52 is the product of the critical current of the Josephson junction 52 times its normal resistance.

Normal resistance is the resistance of Josephson junction 52 in the normal state. The normal state of the Josephson junction is defined as opposed to the superconducting state. In other words, the normal state is not the superconducting state.

Normal resistance depends on temperature. Normal resistance is the benchmark value that is used to compare Josephson junctions made from different technological processes.

Radiation energy defines the depth of penetration of defects into the film-forming material used to make the Josephson junction.

Film is the thin layer of material used to fabricate Josephson 52 junctions.

For example, the material is a mixed oxide of barium, copper and yttrium, denoted YBaCuO. YBaCuO is a crystalline chemical compound frequently having the chemical formula YBa2Cu30 -6, where d is a real number greater than or equal to zero. Preferably, d is between 0 and 0.6.

The irradiation dose determines the number of defects that will be introduced, which qualitatively translates into how the superconductivity in the film material is destroyed.

In the case of an irradiated Josephson junction 52, the resistance of the barrier layer depends on the thickness of the Josephson junction 52, the dose of irradiation and the material forming the barrier layer.

Irradiation is done by bombardment of particles at a given energy.

For example, irradiation is ion irradiation.

Alternatively, the Josephson junctions 52 may be of another type than irradiated Josephson junctions. Josephson junctions 52 can be, for example, grain boundary based Josephson junctions such as "step-edge" Josephson junctions, "bi-crystal" Josephson junctions or "bi-epitaxial" Josephson junctions.

Alternatively, the Josephson junctions 52 may be "ramp" Josephson junctions.

The height of Josephson seams 52 is related to the thickness of the film used.

The dimension of the branches 54 of the Josephson junctions 52 is measured along the second direction Y.

The position of the surfaces of superconducting loops in the network 42 is determined by a set of coordinates in the XYZ frame.

The inductance of component 40 depends on the size of the branches 54 in the second direction Y, on the thickness of the tracks 58 and 60 in the first direction X and on the spacing between the branches 54 measured in the second direction Y.

The inductance of component 40 therefore depends on the geometry of the SQUIDs.

The applicant has selected from these parameters as the initial input parameters of the design process:

- the number of Josephson 52 junctions of the 42 network,

- the position of the Josephson 52 junctions in the network 42,

- the measurement temperature of component 40,

- the value of a supply current of component 40, and

- an initial thickness for each Josephson junction 52, and

- the inductance of component 40.

Also provided is the required response profile of the superconducting component 40, which corresponds to setting at least a target value for peak-to-peak amplitude and slope.

This corresponds to the criterion used in the optimization step which will be described later.

The applicant has chosen as a variable parameter only the thickness of one or more Josephson 52 junctions.

For example, the initial thicknesses of the Josephson junctions 52 are identical.

In the example described, the variable parameters are the thicknesses of each Josephson 52 junction.

The actual optimization is implemented by an iterative approach.

The first iteration takes as a starting point a superconducting component 40 having the initial parameters defined previously. This allows after a simulation calculation to obtain a magnetic field - voltage characteristic for the component.

Specifically, the peak-to-peak amplitude and the characteristic peak slope of the response of the superconducting component 40 are determined.

In the second iteration, at least one parameter of the variable parameters is modified.

The magnetic field - voltage characteristic is then determined with the new parameters.

If the magnetic field - voltage characteristic is better than that of the first iteration, the modification of the variable parameter is retained.

Otherwise, it is discarded.

This way of operating is iterated until it converges on a characteristic magnetic field - voltage that meets the target criterion within a margin.

The margin corresponds, in the example described, to the combination of a first predetermined tolerance value and a second predetermined tolerance value.

Thus, as long as the difference in absolute value between the determined amplitude and the required amplitude is strictly greater than a first predetermined tolerance value and if the difference in absolute value between the determined slope and the required slope is strictly greater than a second predetermined tolerance value, a new iteration is performed.

For example, the first tolerance value is equal to 10% of the required amplitude value.

Similarly, according to an example, the second tolerance value is equal to 10% of the value of the required slope.

The design process thus makes it possible to achieve superconducting components 40 having the desired magnetic field - voltage characteristics and resulting in better sensitivity of the superconducting component 40 considered.

The method makes it possible in particular to increase the number of Josephson junctions 52 arranged in parallel while providing a superconducting component 40 having good sensitivity, in particular due to the better polarization of the Josephson junctions 52 of component 40.

The tests carried out by the applicant have led to the finding of some particularly suitable superconducting components. A first example of a superconducting component is a component conforming to component 40 shown in FIG. 4. In this first example, the thicknesses of the Josephson junctions 52 increase from the central branch 54C towards the outer branches 54.

The greater the Josephson junction 52 has a coordinate in the first direction X whose absolute value is, the greater the thickness of the Josephson junction 52.

For example, on either side of the central branch 54C, the variation in the thickness of the Josephson junctions 52 is identical.

For example, the variation is linear. In other examples, the variation is nonlinear.

According to a second example, in addition to the variation of the first example of component, the area of the superconducting loops formed by two successive Josephson junctions 52 decreases with increasing distance from the central branch 54C.

By way of example, a component comprising identical Josephson junctions and a component 40 with junctions of different thicknesses was tested.

In the test, the first grating 42 of component 40 comprises eleven central 52 Josephson junctions whose thickness is equal to 120 nanometers (nm) in the central region of the grating. The network further comprises, on either side of the central Josephson 52 junctions, Josephson 52 junctions having a thickness varying from 110 nm to 20 nm in steps of 10 nm.

As can be seen in FIG. 5, the response 56 obtained from the superconducting component 40 is particularly satisfactory. The response 56 obtained is characteristic of an SQIF signature. In addition, the characteristic peak 57 obtained is quite distinct. In addition, the peaks of the secondary modulations are also distinguished from the characteristic peak 57.

According to a third example, in addition to the variation of the first example of a component, the area of the superconducting loops formed by two successive Josephson junctions 52 increases with the increase in the distance from the central branch 54C.

By way of illustration of this third example, a component 40 has been tested, the first network 42 of which comprises twenty-seven central Josephson 52 junctions of 40 nm in the central zone of the network 42. In addition, the network comprises, on the other hand and the other of the central Josephson 52 junctions, four Josephson 52 junctions of 100 nm and four Josephson 52 junctions of 110 nm and finally four Josephson junctions of 120 nm.

As can be seen in FIG. 6, the response 56 obtained from the magnetic field - voltage of the superconducting component 40 is particularly satisfactory. Peak 57 characteristic is quite distinct. In particular, peak 57 is distinguished from secondary modulations. This response 56 is to be compared with the response 59 magnetic fields - voltage shown in Figure 7.

In FIG. 7, the response 59 magnetic fields - voltage of a network identical to the network 42 described above in relation to the third example is shown, except that the Josephson junctions 52 of this network have identical thicknesses. In this case, no peak is distinguished from the secondary modulations.

In all of the above cases, the superconducting component 40 obtained comprises at least two Josephson junctions 52 having a different thickness.

For example, the thicknesses of at least two Josephson 52 junctions differ by at least 10 nanometers (nm).

The applicant has thus shown that the fact of adapting the thicknesses of the Josephson junctions 52 in the first network 42 comprising Josephson junctions 52 connected in parallel makes it possible to obtain an optimal response from the superconducting component 40.

The design process thus makes it possible to obtain superconducting components 40 having good sensitivity.

Such a method is advantageously used in a manufacturing process, the manufactured component being the component having the parameters of the component 40 obtained at the output of the design process.

According to more elaborate embodiments, the design method takes into account at least one of the following additional variable parameters:

- the characteristic voltage of each Josephson 52 junction,

- the nature of the material (s) forming the Josephson 52 junctions,

- the energy or irradiation dose of the Josephson 52 junctions when the Josephson junctions are produced by irradiation,

- the critical current of the Josephson 52 junctions,

- the resistance of the barrier layer of the Josephson junctions 52,

- the height of the Josephson 52 junctions,

- the position of the Josephson junctions 52 in the first network 42,

- the position of the surfaces of the superconducting loops formed by two successive Josephson junctions 52 in the first network 42, and - the measurement temperature.

In addition, the design method can also be used for superconducting components 70 having at least one second network 62 connected in series with the first network 42.

For example, the component comprises a plurality of second networks 62 connected in series with each other.

Component 70 then comprises a total number N of networks, the networks of the plurality of networks being electrically connected in series, the method comprising an iteration number at least equal to the total number N of networks.

An example of such a superconducting component 70 is shown in Figure 8.

Claims

1. Method of designing a superconducting component (40, 70), the method being implemented by computer, the component (40, 70) comprising a first network (42) of Josephson junctions (52) electrically connected in parallel. to each other, each Josephson junction (52) having a thickness, the method comprising the steps of:

- provision of initial input parameters of the first network (42) and of a required response profile of the superconducting component (40, 70), the initial input parameters including the number of Josephson junctions (52), the position of the Josephson junctions (52), the measurement temperature of the component (40, 70), the value of a supply current (l _p ) of the component (40, 70) and the initial thickness of each Josephson junction (52) , and

- optimization of the superconducting component (40, 70) by modifying variable parameters to comply with a criterion comprising at least one sub-criterion, the sub-criterion being to minimize the difference in absolute value between the required response profile and the response profile calculated (56), the required response profile being the variation of the voltage at the output of the superconducting component (40, 70) as a function of the variation of a magnetic field external to the superconducting component (40, 70) to which said component is subjected (40, 70) and the variable parameters including the thickness of one or more Josephson junction (s) (52) of the first network (42),

the optimization step being carried out by iteration, the first iteration taking as a starting point a superconducting component (40, 70) having the initial parameters.

2. Design method according to claim 1, wherein the superconducting component (70) comprises at least a second network (62) of Josephson junctions (52) electrically connected in parallel to each other, the second network (62) being electrically. connected in series with the first network (42), wherein the initial input parameters further include the number of Josephson junctions (52) of the second network (62) and the initial thickness of the Josephson junctions (52) of the second network (62) and wherein the variable parameters include the thickness of one or more Josephson junction (s) (52) of the first network (42) and of the second network (62).

3. Design method according to claim 2, wherein the superconducting component (70) comprises a plurality of second networks (62), the superconducting component (70) comprising a total number N of networks (42, 62), the networks ( 42, 62) being electrically connected in series to each other, and wherein the method comprises a number of iterations at least equal to the total number N of networks (42, 62).

4. Design method according to any one of claims 1 to 3, wherein the variable parameters further include at least one element selected from the list consisting of:

- the nature of the material (s) forming the Josephson junctions (52),

- the position of the Josephson junctions (52),

- the measurement temperature,

- the surfaces of the superconducting loops formed by two Josephson junctions (52), the assembly of each loop and the two Josephson junctions (52) forming a superconducting quantum interference device,

- the position of the superconducting loops formed by two Josephson junctions (52), the assembly of each loop and the two Josephson junctions (52) forming a superconducting quantum interference device,

- the energy and / or the irradiation dose of the Josephson junctions (52) when the Josephson junctions are produced by irradiation,

- the critical current of Josephson junctions (52),

- the resistance of the barrier layers of the Josephson junctions (52), and

- the inductance of the superconducting component (40, 70).

The design method according to any one of claims 1 to 4, wherein the required response profile has a characteristic peak (30) having a required amplitude (32) and slope (34), the optimization step. comprising calculating the amplitude and slope of a peak (57) characteristic of the response of the superconducting component (40, 70) as a function of the initial input parameters and determining the difference between the required amplitude ( 32) and the determined amplitude, called the difference in amplitude, and the difference between the required slope (34) and the determined slope, called the difference in slope.

A method of manufacturing a superconducting component (40, 70) designed according to the design method of any one of claims 1 to 5.

7. Computer program product comprising computer program instructions, the computer program instructions being loadable on a data processing unit and being adapted to implement the method according to any one of claims 1 to 6 when the computer program product is executed on a data processing unit.

8. Superconducting component (40, 70) obtainable by implementing the manufacturing process according to claim 6.

9. A superconducting component according to claim 8, comprising a required response profile as being the variation of the output voltage of the superconducting component (40, 70) as a function of the variation of a magnetic field external to the superconducting component (40, 70). ) to which said component (40, 70) is subjected, the required response profile exhibiting a characteristic peak (30) having a required amplitude (32) and slope (34), the superconducting component (40, 70) further comprising , a calculated response profile having a characteristic peak (57) having a calculated amplitude and slope, the calculated response profile of the superconducting component (40, 70) being such that the difference in absolute value between the calculated amplitude and the required amplitude is less than or equal to a first tolerance value and that the difference in absolute value between the calculated slope and the required slope is less than or equal to a second tolerance value.

10. A superconducting component according to claim 9, wherein the first tolerance value is 10% of the required amplitude (32) and the second tolerance value is 10% of the required slope (34).

11. Superconducting component (40, 70) comprising at least one network (42, 62) of Josephson junctions (52) connected to each other electrically in parallel, at least two Josephson junctions (52) each comprising a different thickness.