Adriana Marais

University of Cape Town | UCT · Graduate School of Business

Biological systems are dynamical, constantly exchanging energy and matter with the environment in order to maintain the non-equilibrium state synonymous with living. Developments in observational techniques have allowed us to study biological dynamics on increasingly small scales. Such studies have revealed evidence of quantum mechanical effects, w...

The 66th Lindau Nobel Laureate Meeting (LiNo16) was dedicated to the field of physics. A total of 29 Nobel Laureates, 1 A.M. Turing Award recipient and 400 young scientists attended LiNo16 in Lindau, Germany. Young scientists from 80 countries attended the meeting. Out of the 400 young scientists at the meeting, only 30% were women scientists, and...

A physicochemical description of life and its emergence is one of the greatest open problems in science. Life is made of molecules described fundamentally by quantum theory. The identification of quantum effects in primitive organisms such as bacteria [1,2] has resulted in the successful application of open quantum systems models to energy and char...

Since the emergence of oxygenic photosynthesis, living systems have developed protective mechanisms against reactive oxygen species. During charge separation in photosynthetic reaction centres, triplet states can react with molecular oxygen generating destructive singlet oxygen. The triplet product yield in bacteria is observed to be reduced by wea...

The coherent-one-way and the differential-phase-shift protocols are two of the most recent practical quantum key distribution protocols for quantum cryptography. These protocols belong to a class of so-called distributed-phase-reference quantum key distribution protocols. While security proofs for some limited attacks exist, the unconditional secur...

Quantum biology is the application of the theory of open quantum systems to aspects of biology where classical physics fails to give an accurate de- scription. The most well-established area in quantum biology is the study of photosynthesis. There exists a body of evidence that the primary photosynthetic processes of energy and charge transfer exhi...

It is shown that energy transfer in a homogeneous fully connected quantum network is assisted by a decohering interaction with environmental spins. Analytic expressions for the transfer probabilities are obtained for the zero temperature case, and the effect is shown to persist at physiological temperatures. This model of decoherence-assisted energ...

The dynamics of a dimer coupled to two different environments, each in a spin star configuration under the influence of decoherence, is studied. The exact analytical expression for the transition probability in the dimer system is obtained for different situations, i.e., independent and correlated environments. In all cases considered, it is shown...

The processes of energy and information transfer in quantum networks play an important role for quantum communication and quantum computation. Unavoidable interaction of the quantum system with the environment leads to decoherence and dissipation, processes typically associated with a destruction of quantum coherence in the system. However, recentl...

A necessary condition for the security of a quantum key distribution protocol is that Bob's measurement is described by non-commuting POVM elements. The differential-phase-shift quantum key distribution protocol is formalised, and this condition is shown to be met.

The differential-phase-shift quantum key distribution protocol is formalised as a prepare-and-measure scheme and translated into an equivalent entanglement-based protocol. A necessary condition for security is that Bob's measurement can detect the entanglement of the distributed state in the entanglement-based translation, which implies that his me...

Quantum key distribution (QKD) aims at the creation of a secret key in the two locations of partners, traditionally Alice and Bob, wishing to communi- cate in private. A generic QKD protocol utilises a quantum channel and an authenticated classical channel for exchanges between partners in Phases 1 and 2 of the protocol, respectively. Phase 1 can b...