A German-Spanish collaboration plans to use quantum mechanics (the study of small, inanimate objects such as single atoms) to identify quantum properties in larger and more complex objects made up of tens of millions of atoms, including the flu virus. Details of their unprecedented approach are published in the New Journal of Physics. The study is being supported by the SCALA ('Scalable quantum computing with light and atoms') project, which received EUR 9.36 million under the 'Information society technologies' (IST) Thematic Area of the EU's Sixth Framework Programme (FP6). 'The most striking feature of quantum mechanics is the existence of superposition states, where an object appears to be in different situations at the same time,' the authors write. The existence of these states, they add, has been tested in the past with small objects such as atoms, ions, electrons and photons. However, recent strides in this field have shown that it is possible to create superpositions of collections of photons and atoms. These advancements have inspired the scientists from the Max Planck Institute for Quantum Optics in Germany and the Institute of Photonic Sciences in Spain to construct an experiment to test quantum mechanical phenomena at larger scales. These phenomena include superposition states and entanglement, where matter is physically connected to distant sub-atomic forms. The team is basing their work on the principles of 'Schrödinger's superpositioned cat', an iconic quantum-mechanics thought experiment. Devised in 1935 by Austrian physicist Erwin Schrödinger, the experiment illustrates the quantum theory of superposition through a cat that may be dead or alive, depending on a prior event. The researchers plan to use the precision of lasers to both capture larger objects in a very tiny space known as an 'optical cavity', and to slow the object down into a 'ground state'. They then intend to add a photon to the laser to provoke it into a superposition. They believe the new technique, if successful, could open the door to testing viruses and other large objects. The researchers say: 'We hope that this system, apart from providing new quantum technology, will allow us to test quantum mechanics at larger scales by preparing macroscopic superpositions of objects at the nano and micro scale. This could then enable us to use more complex microorganisms, and thus test the quantum superposition principle with living organisms by performing quantum optics experiments with them. 'We anticipate that our paper will be a starting point for experimentally addressing fundamental questions, such as the role of life and consciousness in quantum mechanics,' the authors conclude.