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Voltage response of non-uniform arrays of bi-superconductive quantum interference devices
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10.1063/1.4712039
/content/aip/journal/jap/111/9/10.1063/1.4712039
http://aip.metastore.ingenta.com/content/aip/journal/jap/111/9/10.1063/1.4712039
View: Figures

Figures

Image of FIG. 1.
FIG. 1.

(Top) Schematic diagram of a dc SQUID magnetometer together with (bottom) the time-averaged voltage response between the two junctions, as a function of the normalized external magnetic flux .

Image of FIG. 2.
FIG. 2.

(Top) Schematic diagram of a dc bi-SQUID magnetometer together with (bottom) its time-averaged voltage response between the two junctions, as a function of the normalized external magnetic flux .

Image of FIG. 3.
FIG. 3.

Circuit representation of a dc bi-SQUID device. “P” is a phase source that accounts for the phase shift due to the external magnetic flux .

Image of FIG. 4.
FIG. 4.

(Top) Numerical simulations of the voltage response of a single bi-SQUID as a function of the critical current . Parameters are , , , , and . (Bottom) Linearity test via linear fitting error and through calculations of SFDR. Observe that best linear response is directly correlated with highest SFDR. Development of cusp for .

Image of FIG. 5.
FIG. 5.

Circuit representation of an array of bi-SQUID devices connected in series. “P” is a phase source that accounts for the phase shift due to the external magnetic flux .

Image of FIG. 6.
FIG. 6.

Numerical simulations of the voltage response of a non-uniform serial bi-SQUID array ( ) as a function of the critical current and external flux . Loop sizes are selected according to a Gaussian distribution. , , , and .

Image of FIG. 7.
FIG. 7.

Linearity test (dashed line) via linear fitting error of the voltage response of an array of equals bi-SQUID devices connected in series as a function of the critical current and corresponding SFDR (solid line). The test shows that there exists a critical current where the error decreases significantly such that the linearity increases. It also shows an optimal value of the critical current where SFDR is optimum and beyond which only marginal improvements in linearity can be achieved.

Image of FIG. 8.
FIG. 8.

Circuit representation of an array of bi-SQUID devices connected in parallel. “P” is a phase source that accounts for the phase shift due to the external magnetic flux .

Image of FIG. 9.
FIG. 9.

Numerical simulations of the voltage response of a non-uniform parallel bi-SQUID array as a function of the critical current and external flux . Loop sizes are selected according to a Gaussian distribution. Other parameters are the same as in Fig. 6 .

Image of FIG. 10.
FIG. 10.

Comparison of the average voltage response as a function of magnetic flux for: a single bi-SQUID (dashed) and two arrays of bi-SQUIDs, one connected in series (black) and one connected in parallel (gray).

Image of FIG. 11.
FIG. 11.

(a) Schematic of a single bi-SQUID cell, rendered in MWO for time domain simulations, including measurement setup for averaging Josephson oscillations. The schematic parameters are chosen as critical current of all three junction are the same, , first two junctions are resistively shunted with , , the third junction is unshunted. . (b) Simulated voltage-flux (control) current response of a single bi-SQUID.

Image of FIG. 12.
FIG. 12.

Simulated voltage-flux (control) current response of 10-cell bi-SQUID SQIF arrays with normal distribution of inductances and junction critical current . Only two junctions are shunted with , , the third junction left unshunted. (a) Serial 10 bi-SQUID SQIF array. (b) Parallel 10 bi-SQUID SQIF array.

Image of FIG. 13.
FIG. 13.

Physical structures of bi-SQUID SQIF arrays implemented using HYPRES superconductor fabrication process: (a) microphotograph of the fabricated serial array fragment, (b) microphotograph of the fabricated parallel array fragment, and (c) the MWO-generated 3D sketch of a bi-SQUID cell from the serial array.

Image of FIG. 14.
FIG. 14.

Microphotographs of the fabricated bi-SQUID-SQIFs integrated on 5 mm × 5 mm chips. (a) Serial meander arrays consisting of 256 bi-SQUID cells. (b) A set of parallel 10 bi-SQUID cell arrays. (c) Serial meander SQIF array with 1445 bi-SQUID cells. (d) Serial spiral SQIF array with 1315 biSQUID cells.

Image of FIG. 15.
FIG. 15.

Measured flux-voltage characteristics of bi-SQUID SQIF arrays: (a) a serial 256 bi-SQUID array. Voltage-flux (V-F) response with , , maximum voltage , coefficient of transformation is for ( is flux quantum); (b) a parallel 10 bi-SQUID array with , , maximum voltage , coefficient of transformation is for ; (c) serial meander 1445-cell array with , ; maximum voltage , coefficient of transformation for ; and (d) serial spiral 1315-cell array with , ; maximum voltage , coefficient of transformation for .

Image of FIG. 16.
FIG. 16.

Spur free dynamic range of an array of dc bi-SQUID loops connected in series.

Image of FIG. 17.
FIG. 17.

Circuit representation of the nearest neighbors of the bi-SQUID in a parallel array. “P” is the normalized applied magnetic flux .

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/content/aip/journal/jap/111/9/10.1063/1.4712039
2012-05-11
2014-04-16
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752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
Scitation: Voltage response of non-uniform arrays of bi-superconductive quantum interference devices
http://aip.metastore.ingenta.com/content/aip/journal/jap/111/9/10.1063/1.4712039
10.1063/1.4712039
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