Development of Electronic Hardware and Software for Advanced Virgo EPR Squeezers
Alessandro Bianchi, Giulia Esposito, Lorenzo Giardini, F. Lombardi, Andrea Marini, Riccardo Mazzoni, Elena Neri, Alessandro Rizzo, Luca Ricci, Gabriele Tomassetti, Marco Valtorta, and Giovanni Zanotti
Quantum Noise (QN) is a phenomenon which gives high contribution to the overall noise in the advanced interferometric Gravitational-Wave Detectors (GWDs). In the previous interferometer generation, the most relevant QN component was dominating in the high frequency region (300Hz–10kHz) of the detection band. This component of noise was attenuated by injection of optimal vacuum squeezed state [1]. In fact, Virgo Scientific Collaboration has already implemented Frequency-Independent Squeezing (FIS) injection to the readout port of Advanced Virgo and reported improvement of the sensitivity curve of around 3dB [2]. Currently, the Collaboration focuses on the work on the FrequencyDependent Squeezing (FDS) injection using a Filter Cavity (FC) which will reduce QN either in the high and low frequency range. At the same time, Virgo Squeezing working group is studying a possible alternative way of producing frequency–dependent squeezed states without the use of FC. The mechanism of FDS without filter cavity, called Einstein–Podolsky–Rosen (EPR) squeezing, was theoretically proposed by Ma et al. [3] and subsequently demonstrated feasible by scientific group from ANU and Hamburg using a proof-of-principle setup [4]. At the moment, development facility for the production of squeezed vacuum at EGO/Virgo site is being adapted for the preliminary experiment on the EPR. This task is carried by the INFN group from Naples and Genova in collaboration with APC. The experiment represents a first step toward implementation of the new squeezing generation technique. For the purpose of the project, INFN group from Perugia together with groups from Pisa, Padova and Rome have been developing various types of photo-detectors and software based on Finite-State Machines (FSMs). In this paper, we overview the current state of work on the facility and we summarize in details the tasks related to the development of electronics and software for implementation of EPR squeezer. In particular, we focus on the engineering of analogue electronics for cavity locking and squeezed state measurement. We conclude by explaining the near future steps: FSM application scheme, noise hunting and operator independent lock acquisition. There are three main motivations for this work. In principle the setup must be as accessible as possible to scientists from various fields of expertise. Thus, its handling must not require any complex operation on the feedback controls, like tuning or calibration. This approach is a first step to minimize necessary human interaction with the subsystem and can be obtained by its automation. Accurate automation will also help us in accomplishing the second goal which is the maximization of the subsystem Quality of Service (QoS). Last but not least, we want to reach the low noise characteristics and keep the subsystem compatible with Virgo infrastructure. We describe below the system developed using custom built devices and various devices built for Virgo. From the optical design of the EPR squeezer shown in Figure 1, we inferred the control system design requirements. In total, we need fourteen feedback loops of various kind: two Optical Phase-Locked Loops (OPLLs) to lock lasers in frequency; two locking loops for non-linear crystal cavities and four for Mode-Cleaner (MC) cavities longitudinal lock, implementing Pound–Drever–Hall technique (PDH); one Proportional–Integral–Derivative controller (PID) for Mach–Zehnder interferometer for light intensity stabilization, two PIDs for Coherent Control (CC) loop for squeezing phase stabilization [5] and yet another three for temperature control loops for non-linear crystals and etalon. Several of these devices need to be fed with a reference frequency. For this purpose we use a custom made 14-channel, synchronous Direct Digital Synthesis (DDS) generator. Actuation on the cavity mirrors is done using high-voltage piezoelectric actuators. We use a custom built amplifier to drive them. In the next two paragraphs we describe the hardware and the software structure of the system.
Quantum Noise (QN) is a phenomenon which gives high contribution to the overall noise in the advanced interferometric Gravitational-Wave Detectors (GWDs). In the previous interferometer generation, the most relevant QN component was dominating in the high frequency region (300Hz–10kHz) of the detection band. This component of noise was attenuated by injection of optimal vacuum squeezed state [1]. In fact, Virgo Scientific Collaboration has already implemented Frequency-Independent Squeezing (FIS) injection to the readout port of Advanced Virgo and reported improvement of the sensitivity curve of around 3dB [2]. Currently, the Collaboration focuses on the work on the FrequencyDependent Squeezing (FDS) injection using a Filter Cavity (FC) which will reduce QN either in the high and low frequency range. At the same time, Virgo Squeezing working group is studying a possible alternative way of producing frequency–dependent squeezed states without the use of FC. The mechanism of FDS without filter cavity, called Einstein–Podolsky–Rosen (EPR) squeezing, was theoretically proposed by Ma et al. [3] and subsequently demonstrated feasible by scientific group from ANU and Hamburg using a proof-of-principle setup [4]. At the moment, development facility for the production of squeezed vacuum at EGO/Virgo site is being adapted for the preliminary experiment on the EPR. This task is carried by the INFN group from Naples and Genova in collaboration with APC. The experiment represents a first step toward implementation of the new squeezing generation technique. For the purpose of the project, INFN group from Perugia together with groups from Pisa, Padova and Rome have been developing various types of photo-detectors and software based on Finite-State Machines (FSMs). In this paper, we overview the current state of work on the facility and we summarize in details the tasks related to the development of electronics and software for implementation of EPR squeezer. In particular, we focus on the engineering of analogue electronics for cavity locking and squeezed state measurement. We conclude by explaining the near future steps: FSM application scheme, noise hunting and operator independent lock acquisition. There are three main motivations for this work. In principle the setup must be as accessible as possible to scientists from various fields of expertise. Thus, its handling must not require any complex operation on the feedback controls, like tuning or calibration. This approach is a first step to minimize necessary human interaction with the subsystem and can be obtained by its automation. Accurate automation will also help us in accomplishing the second goal which is the maximization of the subsystem Quality of Service (QoS). Last but not least, we want to reach the low noise characteristics and keep the subsystem compatible with Virgo infrastructure. We describe below the system developed using custom built devices and various devices built for Virgo. From the optical design of the EPR squeezer shown in Figure 1, we inferred the control system design requirements. In total, we need fourteen feedback loops of various kind: two Optical Phase-Locked Loops (OPLLs) to lock lasers in frequency; two locking loops for non-linear crystal cavities and four for Mode-Cleaner (MC) cavities longitudinal lock, implementing Pound–Drever–Hall technique (PDH); one Proportional–Integral–Derivative controller (PID) for Mach–Zehnder interferometer for light intensity stabilization, two PIDs for Coherent Control (CC) loop for squeezing phase stabilization [5] and yet another three for temperature control loops for non-linear crystals and etalon. Several of these devices need to be fed with a reference frequency. For this purpose we use a custom made 14-channel, synchronous Direct Digital Synthesis (DDS) generator. Actuation on the cavity mirrors is done using high-voltage piezoelectric actuators. We use a custom built amplifier to drive them. In the next two paragraphs we describe the hardware and the software structure of the system.
Quantum Noise (QN) is a phenomenon which gives high contribution to the overall noise in the advanced interferometric Gravitational-Wave Detectors (GWDs). In the previous interferometer generation, the most relevant QN component was dominating in the high frequency region (300Hz–10kHz) of the detection band. This component of noise was attenuated by injection of optimal vacuum squeezed state [1]. In fact, Virgo Scientific Collaboration has already implemented Frequency-Independent Squeezing (FIS) injection to the readout port of Advanced Virgo and reported improvement of the sensitivity curve of around 3dB [2]. Currently, the Collaboration focuses on the work on the FrequencyDependent Squeezing (FDS) injection using a Filter Cavity (FC) which will reduce QN either in the high and low frequency range. At the same time, Virgo Squeezing working group is studying a possible alternative way of producing frequency–dependent squeezed states without the use of FC. The mechanism of FDS without filter cavity, called Einstein–Podolsky–Rosen (EPR) squeezing, was theoretically proposed by Ma et al. [3] and subsequently demonstrated feasible by scientific group from ANU and Hamburg using a proof-of-principle setup [4]. At the moment, development facility for the production of squeezed vacuum at EGO/Virgo site is being adapted for the preliminary experiment on the EPR. This task is carried by the INFN group from Naples and Genova in collaboration with APC. The experiment represents a first step toward implementation of the new squeezing generation technique. For the purpose of the project, INFN group from Perugia together with groups from Pisa, Padova and Rome have been developing various types of photo-detectors and software based on Finite-State Machines (FSMs). In this paper, we overview the current state of work on the facility and we summarize in details the tasks related to the development of electronics and software for implementation of EPR squeezer. In particular, we focus on the engineering of analogue electronics for cavity locking and squeezed state measurement. We conclude by explaining the near future steps: FSM application scheme, noise hunting and operator independent lock acquisition. There are three main motivations for this work. In principle the setup must be as accessible as possible to scientists from various fields of expertise. Thus, its handling must not require any complex operation on the feedback controls, like tuning or calibration. This approach is a first step to minimize necessary human interaction with the subsystem and can be obtained by its automation. Accurate automation will also help us in accomplishing the second goal which is the maximization of the subsystem Quality of Service (QoS). Last but not least, we want to reach the low noise characteristics and keep the subsystem compatible with Virgo infrastructure. We describe below the system developed using custom built devices and various devices built for Virgo. From the optical design of the EPR squeezer shown in Figure 1, we inferred the control system design requirements. In total, we need fourteen feedback loops of various kind: two Optical Phase-Locked Loops (OPLLs) to lock lasers in frequency; two locking loops for non-linear crystal cavities and four for Mode-Cleaner (MC) cavities longitudinal lock, implementing Pound–Drever–Hall technique (PDH); one Proportional–Integral–Derivative controller (PID) for Mach–Zehnder interferometer for light intensity stabilization, two PIDs for Coherent Control (CC) loop for squeezing phase stabilization [5] and yet another three for temperature control loops for non-linear crystals and etalon. Several of these devices need to be fed with a reference frequency. For this purpose we use a custom made 14-channel, synchronous Direct Digital Synthesis (DDS) generator. Actuation on the cavity mirrors is done using high-voltage piezoelectric actuators. We use a custom built amplifier to drive them. In the next two paragraphs we describe the hardware and the software structure of the system.
Quantum Noise (QN) is a phenomenon which gives high contribution to the overall noise in the advanced interferometric Gravitational-Wave Detectors (GWDs). In the previous interferometer generation, the most relevant QN component was dominating in the high frequency region (300Hz–10kHz) of the detection band. This component of noise was attenuated by injection of optimal vacuum squeezed state [1]. In fact, Virgo Scientific Collaboration has already implemented Frequency-Independent Squeezing (FIS) injection to the readout port of Advanced Virgo and reported improvement of the sensitivity curve of around 3dB [2]. Currently, the Collaboration focuses on the work on the FrequencyDependent Squeezing (FDS) injection using a Filter Cavity (FC) which will reduce QN either in the high and low frequency range. At the same time, Virgo Squeezing working group is studying a possible alternative way of producing frequency–dependent squeezed states without the use of FC. The mechanism of FDS without filter cavity, called Einstein–Podolsky–Rosen (EPR) squeezing, was theoretically proposed by Ma et al. [3] and subsequently demonstrated feasible by scientific group from ANU and Hamburg using a proof-of-principle setup [4]. At the moment, development facility for the production of squeezed vacuum at EGO/Virgo site is being adapted for the preliminary experiment on the EPR. This task is carried by the INFN group from Naples and Genova in collaboration with APC. The experiment represents a first step toward implementation of the new squeezing generation technique. For the purpose of the project, INFN group from Perugia together with groups from Pisa, Padova and Rome have been developing various types of photo-detectors and software based on Finite-State Machines (FSMs). In this paper, we overview the current state of work on the facility and we summarize in details the tasks related to the development of electronics and software for implementation of EPR squeezer. In particular, we focus on the engineering of analogue electronics for cavity locking and squeezed state measurement. We conclude by explaining the near future steps: FSM application scheme, noise hunting and operator independent lock acquisition. There are three main motivations for this work. In principle the setup must be as accessible as possible to scientists from various fields of expertise. Thus, its handling must not require any complex operation on the feedback controls, like tuning or calibration. This approach is a first step to minimize necessary human interaction with the subsystem and can be obtained by its automation. Accurate automation will also help us in accomplishing the second goal which is the maximization of the subsystem Quality of Service (QoS). Last but not least, we want to reach the low noise characteristics and keep the subsystem compatible with Virgo infrastructure. We describe below the system developed using custom built devices and various devices built for Virgo. From the optical design of the EPR squeezer shown in Figure 1, we inferred the control system design requirements. In total, we need fourteen feedback loops of various kind: two Optical Phase-Locked Loops (OPLLs) to lock lasers in frequency; two locking loops for non-linear crystal cavities and four for Mode-Cleaner (MC) cavities longitudinal lock, implementing Pound–Drever–Hall technique (PDH); one Proportional–Integral–Derivative controller (PID) for Mach–Zehnder interferometer for light intensity stabilization, two PIDs for Coherent Control (CC) loop for squeezing phase stabilization [5] and yet another three for temperature control loops for non-linear crystals and etalon. Several of these devices need to be fed with a reference frequency. For this purpose we use a custom made 14-channel, synchronous Direct Digital Synthesis (DDS) generator. Actuation on the cavity mirrors is done using high-voltage piezoelectric actuators. We use a custom built amplifier to drive them. In the next two paragraphs we describe the hardware and the software structure of the system.
Quantum Noise (QN) is a phenomenon which gives high contribution to the overall noise in the advanced interferometric Gravitational-Wave Detectors (GWDs). In the previous interferometer generation, the most relevant QN component was dominating in the high frequency region (300Hz–10kHz) of the detection band. This component of noise was attenuated by injection of optimal vacuum squeezed state [1]. In fact, Virgo Scientific Collaboration has already implemented Frequency-Independent Squeezing (FIS) injection to the readout port of Advanced Virgo and reported improvement of the sensitivity curve of around 3dB [2]. Currently, the Collaboration focuses on the work on the FrequencyDependent Squeezing (FDS) injection using a Filter Cavity (FC) which will reduce QN either in the high and low frequency range. At the same time, Virgo Squeezing working group is studying a possible alternative way of producing frequency–dependent squeezed states without the use of FC. The mechanism of FDS without filter cavity, called Einstein–Podolsky–Rosen (EPR) squeezing, was theoretically proposed by Ma et al. [3] and subsequently demonstrated feasible by scientific group from ANU and Hamburg using a proof-of-principle setup [4]. At the moment, development facility for the production of squeezed vacuum at EGO/Virgo site is being adapted for the preliminary experiment on the EPR. This task is carried by the INFN group from Naples and Genova in collaboration with APC. The experiment represents a first step toward implementation of the new squeezing generation technique. For the purpose of the project, INFN group from Perugia together with groups from Pisa, Padova and Rome have been developing various types of photo-detectors and software based on Finite-State Machines (FSMs). In this paper, we overview the current state of work on the facility and we summarize in details the tasks related to the development of electronics and software for implementation of EPR squeezer. In particular, we focus on the engineering of analogue electronics for cavity locking and squeezed state measurement. We conclude by explaining the near future steps: FSM application scheme, noise hunting and operator independent lock acquisition. There are three main motivations for this work. In principle the setup must be as accessible as possible to scientists from various fields of expertise. Thus, its handling must not require any complex operation on the feedback controls, like tuning or calibration. This approach is a first step to minimize necessary human interaction with the subsystem and can be obtained by its automation. Accurate automation will also help us in accomplishing the second goal which is the maximization of the subsystem Quality of Service (QoS). Last but not least, we want to reach the low noise characteristics and keep the subsystem compatible with Virgo infrastructure. We describe below the system developed using custom built devices and various devices built for Virgo. From the optical design of the EPR squeezer shown in Figure 1, we inferred the control system design requirements. In total, we need fourteen feedback loops of various kind: two Optical Phase-Locked Loops (OPLLs) to lock lasers in frequency; two locking loops for non-linear crystal cavities and four for Mode-Cleaner (MC) cavities longitudinal lock, implementing Pound–Drever–Hall technique (PDH); one Proportional–Integral–Derivative controller (PID) for Mach–Zehnder interferometer for light intensity stabilization, two PIDs for Coherent Control (CC) loop for squeezing phase stabilization [5] and yet another three for temperature control loops for non-linear crystals and etalon. Several of these devices need to be fed with a reference frequency. For this purpose we use a custom made 14-channel, synchronous Direct Digital Synthesis (DDS) generator. Actuation on the cavity mirrors is done using high-voltage piezoelectric actuators. We use a custom built amplifier to drive them. In the next two paragraphs we describe the hardware and the software structure of the system.
Quantum Noise (QN) is a phenomenon which gives high contribution to the overall noise in the advanced interferometric Gravitational-Wave Detectors (GWDs). In the previous interferometer generation, the most relevant QN component was dominating in the high frequency region (300Hz–10kHz) of the detection band. This component of noise was attenuated by injection of optimal vacuum squeezed state [1]. In fact, Virgo Scientific Collaboration has already implemented Frequency-Independent Squeezing (FIS) injection to the readout port of Advanced Virgo and reported improvement of the sensitivity curve of around 3dB [2]. Currently, the Collaboration focuses on the work on the FrequencyDependent Squeezing (FDS) injection using a Filter Cavity (FC) which will reduce QN either in the high and low frequency range. At the same time, Virgo Squeezing working group is studying a possible alternative way of producing frequency–dependent squeezed states without the use of FC. The mechanism of FDS without filter cavity, called Einstein–Podolsky–Rosen (EPR) squeezing, was theoretically proposed by Ma et al. [3] and subsequently demonstrated feasible by scientific group from ANU and Hamburg using a proof-of-principle setup [4]. At the moment, development facility for the production of squeezed vacuum at EGO/Virgo site is being adapted for the preliminary experiment on the EPR. This task is carried by the INFN group from Naples and Genova in collaboration with APC. The experiment represents a first step toward implementation of the new squeezing generation technique. For the purpose of the project, INFN group from Perugia together with groups from Pisa, Padova and Rome have been developing various types of photo-detectors and software based on Finite-State Machines (FSMs). In this paper, we overview the current state of work on the facility and we summarize in details the tasks related to the development of electronics and software for implementation of EPR squeezer. In particular, we focus on the engineering of analogue electronics for cavity locking and squeezed state measurement. We conclude by explaining the near future steps: FSM application scheme, noise hunting and operator independent lock acquisition. There are three main motivations for this work. In principle the setup must be as accessible as possible to scientists from various fields of expertise. Thus, its handling must not require any complex operation on the feedback controls, like tuning or calibration. This approach is a first step to minimize necessary human interaction with the subsystem and can be obtained by its automation. Accurate automation will also help us in accomplishing the second goal which is the maximization of the subsystem Quality of Service (QoS). Last but not least, we want to reach the low noise characteristics and keep the subsystem compatible with Virgo infrastructure. We describe below the system developed using custom built devices and various devices built for Virgo. From the optical design of the EPR squeezer shown in Figure 1, we inferred the control system design requirements. In total, we need fourteen feedback loops of various kind: two Optical Phase-Locked Loops (OPLLs) to lock lasers in frequency; two locking loops for non-linear crystal cavities and four for Mode-Cleaner (MC) cavities longitudinal lock, implementing Pound–Drever–Hall technique (PDH); one Proportional–Integral–Derivative controller (PID) for Mach–Zehnder interferometer for light intensity stabilization, two PIDs for Coherent Control (CC) loop for squeezing phase stabilization [5] and yet another three for temperature control loops for non-linear crystals and etalon. Several of these devices need to be fed with a reference frequency. For this purpose we use a custom made 14-channel, synchronous Direct Digital Synthesis (DDS) generator. Actuation on the cavity mirrors is done using high-voltage piezoelectric actuators. We use a custom built amplifier to drive them. In the next two paragraphs we describe the hardware and the software structure of the system.
Quantum Noise (QN) is a phenomenon which gives high contribution to the overall noise in the advanced interferometric Gravitational-Wave Detectors (GWDs). In the previous interferometer generation, the most relevant QN component was dominating in the high frequency region (300Hz–10kHz) of the detection band. This component of noise was attenuated by injection of optimal vacuum squeezed state [1]. In fact, Virgo Scientific Collaboration has already implemented Frequency-Independent Squeezing (FIS) injection to the readout port of Advanced Virgo and reported improvement of the sensitivity curve of around 3dB [2]. Currently, the Collaboration focuses on the work on the FrequencyDependent Squeezing (FDS) injection using a Filter Cavity (FC) which will reduce QN either in the high and low frequency range. At the same time, Virgo Squeezing working group is studying a possible alternative way of producing frequency–dependent squeezed states without the use of FC. The mechanism of FDS without filter cavity, called Einstein–Podolsky–Rosen (EPR) squeezing, was theoretically proposed by Ma et al. [3] and subsequently demonstrated feasible by scientific group from ANU and Hamburg using a proof-of-principle setup [4]. At the moment, development facility for the production of squeezed vacuum at EGO/Virgo site is being adapted for the preliminary experiment on the EPR. This task is carried by the INFN group from Naples and Genova in collaboration with APC. The experiment represents a first step toward implementation of the new squeezing generation technique. For the purpose of the project, INFN group from Perugia together with groups from Pisa, Padova and Rome have been developing various types of photo-detectors and software based on Finite-State Machines (FSMs). In this paper, we overview the current state of work on the facility and we summarize in details the tasks related to the development of electronics and software for implementation of EPR squeezer. In particular, we focus on the engineering of analogue electronics for cavity locking and squeezed state measurement. We conclude by explaining the near future steps: FSM application scheme, noise hunting and operator independent lock acquisition. There are three main motivations for this work. In principle the setup must be as accessible as possible to scientists from various fields of expertise. Thus, its handling must not require any complex operation on the feedback controls, like tuning or calibration. This approach is a first step to minimize necessary human interaction with the subsystem and can be obtained by its automation. Accurate automation will also help us in accomplishing the second goal which is the maximization of the subsystem Quality of Service (QoS). Last but not least, we want to reach the low noise characteristics and keep the subsystem compatible with Virgo infrastructure. We describe below the system developed using custom built devices and various devices built for Virgo. From the optical design of the EPR squeezer shown in Figure 1, we inferred the control system design requirements. In total, we need fourteen feedback loops of various kind: two Optical Phase-Locked Loops (OPLLs) to lock lasers in frequency; two locking loops for non-linear crystal cavities and four for Mode-Cleaner (MC) cavities longitudinal lock, implementing Pound–Drever–Hall technique (PDH); one Proportional–Integral–Derivative controller (PID) for Mach–Zehnder interferometer for light intensity stabilization, two PIDs for Coherent Control (CC) loop for squeezing phase stabilization [5] and yet another three for temperature control loops for non-linear crystals and etalon. Several of these devices need to be fed with a reference frequency. For this purpose we use a custom made 14-channel, synchronous Direct Digital Synthesis (DDS) generator. Actuation on the cavity mirrors is done using high-voltage piezoelectric actuators. We use a custom built amplifier to drive them. In the next two paragraphs we describe the hardware and the software structure of the system.
Quantum Noise (QN) is a phenomenon which gives high contribution to the overall noise in the advanced interferometric Gravitational-Wave Detectors (GWDs). In the previous interferometer generation, the most relevant QN component was dominating in the high frequency region (300Hz–10kHz) of the detection band. This component of noise was attenuated by injection of optimal vacuum squeezed state [1]. In fact, Virgo Scientific Collaboration has already implemented Frequency-Independent Squeezing (FIS) injection to the readout port of Advanced Virgo and reported improvement of the sensitivity curve of around 3dB [2]. Currently, the Collaboration focuses on the work on the FrequencyDependent Squeezing (FDS) injection using a Filter Cavity (FC) which will reduce QN either in the high and low frequency range. At the same time, Virgo Squeezing working group is studying a possible alternative way of producing frequency–dependent squeezed states without the use of FC. The mechanism of FDS without filter cavity, called Einstein–Podolsky–Rosen (EPR) squeezing, was theoretically proposed by Ma et al. [3] and subsequently demonstrated feasible by scientific group from ANU and Hamburg using a proof-of-principle setup [4]. At the moment, development facility for the production of squeezed vacuum at EGO/Virgo site is being adapted for the preliminary experiment on the EPR. This task is carried by the INFN group from Naples and Genova in collaboration with APC. The experiment represents a first step toward implementation of the new squeezing generation technique. For the purpose of the project, INFN group from Perugia together with groups from Pisa, Padova and Rome have been developing various types of photo-detectors and software based on Finite-State Machines (FSMs). In this paper, we overview the current state of work on the facility and we summarize in details the tasks related to the development of electronics and software for implementation of EPR squeezer. In particular, we focus on the engineering of analogue electronics for cavity locking and squeezed state measurement. We conclude by explaining the near future steps: FSM application scheme, noise hunting and operator independent lock acquisition. There are three main motivations for this work. In principle the setup must be as accessible as possible to scientists from various fields of expertise. Thus, its handling must not require any complex operation on the feedback controls, like tuning or calibration. This approach is a first step to minimize necessary human interaction with the subsystem and can be obtained by its automation. Accurate automation will also help us in accomplishing the second goal which is the maximization of the subsystem Quality of Service (QoS). Last but not least, we want to reach the low noise characteristics and keep the subsystem compatible with Virgo infrastructure. We describe below the system developed using custom built devices and various devices built for Virgo. From the optical design of the EPR squeezer shown in Figure 1, we inferred the control system design requirements. In total, we need fourteen feedback loops of various kind: two Optical Phase-Locked Loops (OPLLs) to lock lasers in frequency; two locking loops for non-linear crystal cavities and four for Mode-Cleaner (MC) cavities longitudinal lock, implementing Pound–Drever–Hall technique (PDH); one Proportional–Integral–Derivative controller (PID) for Mach–Zehnder interferometer for light intensity stabilization, two PIDs for Coherent Control (CC) loop for squeezing phase stabilization [5] and yet another three for temperature control loops for non-linear crystals and etalon. Several of these devices need to be fed with a reference frequency. For this purpose we use a custom made 14-channel, synchronous Direct Digital Synthesis (DDS) generator. Actuation on the cavity mirrors is done using high-voltage piezoelectric actuators. We use a custom built amplifier to drive them. In the next two paragraphs we describe the hardware and the software structure of the system.