 Hello, everyone. My name is Balik Abdul. I am from IBM Research. In this talk, we are going to present an on-chip Jocelyn isolator that uses a single pump drive for its operation. And then we will show how we use it with other superconducting microwave components to achieve a high fidelity qubit readout. But first, why do we need non-reciprocal devices such as circulators and isolators? We need them because they play several important roles in a high fidelity Q and D qubit measurement schemes that are required in superconducting quantum computing. They route the readout signal in a directional manner. They separate input from output. And they protect the quantum system from noise coming from the output chain. However, a set of the arc circulators and isolators that are used nowadays are prohibitive in scalable architectures, as you can see on the right side of the slide. This is because they are bulky and they rely on magnetic materials and some magnetic fields that are difficult to integrate on-chip and incompatible with superconducting circuits. To tackle this scalability challenge and avoid these disadvantages, we implemented in this paper on this slide an interferometric jostling isolator. And the main building block of this isolator is the jostling parametric converter, JPC. As you can see here in this block diagram of this isolator, it's built by coupling two identical JPCs in an interferometric scheme. In this scheme, mode A of the JPCs are coupled via a 90-degree hybrid. And mode B of the JPCs are coupled to 50-ohm terminations and an intermediate transmission line. By operating this device in the frequency conversion mode and setting the phase difference between the microdrive to be pi over 2, then we can generate a non-reciprocal response that is indicated by this arrow here. So a signal that is propagating in the direction of the arrow will be transmitted from port 1 to 2, but a signal that is propagating in the opposite direction will be blocked. In particular, if we operate the device or the JPCs at a 50-50 beam splitter point where half of the signal is reflected and half of it is transmitted by and undergoes a frequency conversion, then we can show in theory that we get almost a near-unit transmission in S21 and vanishing parameters in the opposite direction and reflection parameters. So previously we implemented this isolator scheme in the form of an integrated circuit. We integrated the two JPCs into a printed circuit board that contains the 90-degree hybrid and the transmission line. We also showed that the device works as an isolator. For example, by setting the phase difference between the two pumps, feeding the two JPCs to be pi over 2, then the directionality is from a port 1 to 2, and indeed when we measure the transmission parameters versus a signal frequency, we see almost a near-unit transmission in S21 but a large dip in S12. If we shift this phase difference by pi, we see that the device response is reversed as expected. This result, although the device works, it has two main drawbacks. One is that it's a hybrid of normal and subconducting circuits and the second, it requires for its operation, two pumps or at least two input lines in the fridge. So in this work, we realized an on-shape, just an isolator that uses a single pump drive, as you can see here in the photos at the bottom. And in this new device, the 90-degree hybrid and the two JPCs and the transmission line are also pre-conducting and implemented on the same chip. And we implemented on the same chip a 90-degree hybrid for the pump drive that is coupled to the feed lines of the two JPCs. Since this 90-degree hybrid splits the pump power evenly between the two stages and imposes the required phase difference by design, we are able to operate this device using a single pump atone. These changes lead to several advantages. They, such as reduction in the microwave, the number of microwave sources, easier tune-up procedures, enhanced stability over time, simpler control and reduced losses. So when we measure the transmission parameters of this device versus the signal frequency, we see that the device works and acts as an isolator, as you can see here. And we see that we are able to generate almost a unity transmission of the transmission in one direction and a strong isolation in the opposite direction, depending on which port we are feeding the pump to. Also, we see that the reflection parameters remain small whether the pump is on and off. Moreover, these results are important because they provide an experimental conformation to the theory prediction that the phase gradient condition for non-respirosity is plus and minus pi over 2 and not any other phases. Next, we can flux-tune our device to a certain center frequency and we can vary the pump power while keeping the pump frequency fixed. As you can see here in these graphs, the device response is monotonic and stable, very similar to the observed response of JPAs and JPCs. We also measured the tunable bandwidth of the device and we find that it's about 300 MHz. In this measurement, we flux-tune the two jostling modulators of the JPCs in tandem and for each flux working point, we adjust the pump frequency and the frequency of the power to yield an isolation of at least 15 dB, depending on in the direction that depends on where we are feeding the pump into. In this slide, we are showing one remarkable result of this work. It demonstrates that the sign of the directionality or the transmission and isolation direction is determined not only by the port in which you feed the pump to, but also on the parity of the magnetic fluxes threading the two jostling modulators or the parity of the circulating currents flowing in these jostling modulators, which in turn determines the sign of the coupling between the modes. What you see here is that if we keep the pump drive the same and we feed it into the same port, then we can reverse the non-reciprocity by flipping the flux in one loop like you see on the right side or you can preserve this directionality by flipping the fluxes in two loops. This result opens the door for a detection of the orientation of weak magnetic sources using simple, simple microwave transmission measurements. Following these results, we went a few steps further. We built a motherboard that could replace the isolators and circulators that we use in our high-fidelity readout chains. On the top, you see the layer of the current coming out of this motherboard. At the bottom, you see a photo of it. This motherboard integrates several components, a parcel filter, a superconducting directional coupler, two jostling isolators and one jostling directional amplifier. The motherboard has a few ports in which we feed the pump drives to power these jostling devices and it has three main ports. One is the readout that is coupled to the readout input line. One is that's connected to the cube chip and the third one is connected to the readout output line. When we measure this device with the superconducting qubit coupled to a readout resonator and without any intermediate circulators and isolators, we achieve a high-fidelity readout and good coherence. More specifically, if we turn on the first jostling isolator and the first directional amplifier, unfortunately in this experiment, the second jostling isolator got damaged during wire bonding, so it wasn't part of this experiment. We get a fidelity of 92 percent and we preserve T1 and maintain 75 percent of T2 echo when compared to the baseline case in which these jostling isolators are off. Looking forward, we would like to realize a single pump version of this directional amplifier. We would like to improve the components of this motherboard to maintain T2 echo and we would like to enhance the saturation power and bandwidth of these jostling components to support a multiplex readout. Thank you very much.