In this episode of the Physics World Weekly podcast, we speak to Mirella Koleva and Gaby Slavcheva, who are the co-founders of the UK-based company Quantopticon. The firm develops software for simulating quantum photonics devices and Koleva and Slavcheva explain why there is a need to understand the fundamental physics behind the devices that underpin the latest quantum technologies. They also talk about the importance of start-up accelerators for companies like Quantopticon.

Also in this episode, we hear from a physicist who has struggled within the mental health system. After a horrific reaction to a medication and multiple diagnoses that got him nowhere, Alexander Mendelsohn (not his real name) explains why he believes that the mental-health system operates in a bizarre, awful and unscientific way. He also explains why his physics background makes him wonder why more quantitative rigour is not used in treating mental illness.

• Mendelsohn also describes his experiences in this article in Physics World: “A physicist’s experience of the mental-health system”.